Merge branch 'hdf5_1_8' of https://bitbucket.hdfgroup.org/scm/~bmribler/hdf5_1_8_bmr into hdf5_1_8

39 files changed, 256 insertions, 142 deletions

diff --git a/release_docs/RELEASE.txt b/release_docs/RELEASE.txt
index eb9f0d9..ad06d40 100644
--- a/release_docs/RELEASE.txt
+++ b/release_docs/RELEASE.txt
@@ -155,6 +155,77 @@ Bug Fixes since HDF5-1.8.20
 
       (DER - 2018/02/06, HDFFV-10354)
 
+    - If an HDF5 file contains a filter pipeline message which contains
+      a 'number of filters' field that exceeds the actual number of
+      filters in the message, the HDF5 C library will read off the end of
+      the read buffer.
+
+      This issue was reported to The HDF Group as issue #CVE-2017-17506.
+
+      NOTE: The HDF5 C library cannot produce such a file. This condition
+            should only occur in a corrupt (or deliberately altered) file
+            or a file created by third-party software.
+
+      The problem was fixed by passing the buffer size with the buffer
+      and ensuring that the pointer cannot be incremented off the end
+      of the buffer. A mismatch between the number of filters declared
+      and the actual number of filters will now invoke normal HDF5
+      error handling.
+
+      (DER - 2018/02/26, HDFFV-10355)
+
+    - If an HDF5 file contains a malformed compound datatype with a
+      suitably large offset, the type conversion code can run off
+      the end of the type conversion buffer, causing a segmentation
+      fault.
+
+      This issue was reported to The HDF Group as issue #CVE-2017-17507.
+
+      NOTE: The HDF5 C library cannot produce such a file. This condition
+            should only occur in a corrupt (or deliberately altered) file
+            or a file created by third-party software.
+
+      THE HDF GROUP WILL NOT FIX THIS BUG AT THIS TIME
+
+      Fixing this problem would involve updating the publicly visible
+      H5T_conv_t function pointer typedef and versioning the API calls
+      which use it. We normally only modify the public API during
+      major releases, so this bug will not be fixed at this time.
+
+      (DER - 2018/02/26, HDFFV-10356)
+
+    - If an HDF5 file contains a malformed compound type which contains
+      a member of size zero, a division by zero error will occur while
+      processing the type.
+
+      This issue was reported to The HDF Group as issue #CVE-2017-17508.
+
+      NOTE: The HDF5 C library cannot produce such a file. This condition
+            should only occur in a corrupt (or deliberately altered) file
+            or a file created by third-party software.
+
+      Checking for zero before dividing fixes the problem. Instead of the
+      division by zero, the normal HDF5 error handling is invoked.
+
+      (DER - 2018/02/26, HDFFV-10357)
+
+    - If an HDF5 file contains a malformed symbol table node that declares
+      it contains more symbols than it actually contains, the library
+      can run off the end of the metadata cache buffer while processing
+      the symbol table node.
+
+      This issue was reported to The HDF Group as issue #CVE-2017-17509.
+
+      NOTE: The HDF5 C library cannot produce such a file. This condition
+            should only occur in a corrupt (or deliberately altered) file
+            or a file created by third-party software.
+
+      Performing bounds checks on the buffer while processing fixes the
+      problem. Instead of the segmentation fault, the normal HDF5 error
+      handling is invoked.
+
+      (DER - 2018/03/12, HDFFV-10358)
+
     Configuration
     -------------
     - CMake
diff --git a/src/H5Abtree2.c b/src/H5Abtree2.c
index 33a031e..318c60d 100644
--- a/src/H5Abtree2.c
+++ b/src/H5Abtree2.c
@@ -162,7 +162,7 @@ const H5B2_class_t H5A_BT2_CORDER[1]={{ /* B-tree class information */
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5A_dense_fh_name_cmp(const void *obj, size_t H5_ATTR_UNUSED obj_len, void *_udata)
+H5A_dense_fh_name_cmp(const void *obj, size_t obj_len, void *_udata)
 {
     H5A_fh_ud_cmp_t *udata = (H5A_fh_ud_cmp_t *)_udata;         /* User data for 'op' callback */
     H5A_t *attr = NULL;                 /* Pointer to attribute created from heap object */
@@ -172,7 +172,7 @@ H5A_dense_fh_name_cmp(const void *obj, size_t H5_ATTR_UNUSED obj_len, void *_uda
     FUNC_ENTER_NOAPI_NOINIT
 
     /* Decode attribute information */
-    if(NULL == (attr = (H5A_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_ATTR_ID, (const unsigned char *)obj)))
+    if(NULL == (attr = (H5A_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_ATTR_ID, obj_len, (const unsigned char *)obj)))
         HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, FAIL, "can't decode attribute")
 
     /* Compare the string values */
diff --git a/src/H5Adense.c b/src/H5Adense.c
index 291f422..ab159ff 100644
--- a/src/H5Adense.c
+++ b/src/H5Adense.c
@@ -843,7 +843,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5A__dense_copy_fh_cb(const void *obj, size_t H5_ATTR_UNUSED obj_len, void *_udata)
+H5A__dense_copy_fh_cb(const void *obj, size_t obj_len, void *_udata)
 {
     H5A_fh_ud_cp_t *udata = (H5A_fh_ud_cp_t *)_udata;       /* User data for fractal heap 'op' callback */
     herr_t ret_value = SUCCEED;   /* Return value */
@@ -857,7 +857,7 @@ H5A__dense_copy_fh_cb(const void *obj, size_t H5_ATTR_UNUSED obj_len, void *_uda
      *  HDF5 routine, it could attempt to re-protect that direct block for the
      *  heap, causing the HDF5 routine called to fail)
      */
-    if(NULL == (udata->attr = (H5A_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_ATTR_ID, (const unsigned char *)obj)))
+    if(NULL == (udata->attr = (H5A_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_ATTR_ID, obj_len, (const unsigned char *)obj)))
         HGOTO_ERROR(H5E_ATTR, H5E_CANTDECODE, FAIL, "can't decode attribute")
 
     /* Set the creation order index for the attribute */
diff --git a/src/H5Gbtree2.c b/src/H5Gbtree2.c
index 888c611..d520484 100644
--- a/src/H5Gbtree2.c
+++ b/src/H5Gbtree2.c
@@ -159,7 +159,7 @@ const H5B2_class_t H5G_BT2_CORDER[1]={{ /* B-tree class information */
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5G_dense_fh_name_cmp(const void *obj, size_t H5_ATTR_UNUSED obj_len, void *_udata)
+H5G_dense_fh_name_cmp(const void *obj, size_t obj_len, void *_udata)
 {
     H5G_fh_ud_cmp_t *udata = (H5G_fh_ud_cmp_t *)_udata;         /* User data for 'op' callback */
     H5O_link_t *lnk;    /* Pointer to link created from heap object */
@@ -168,7 +168,7 @@ H5G_dense_fh_name_cmp(const void *obj, size_t H5_ATTR_UNUSED obj_len, void *_uda
     FUNC_ENTER_NOAPI_NOINIT
 
     /* Decode link information */
-    if(NULL == (lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_LINK_ID, (const unsigned char *)obj)))
+    if(NULL == (lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_LINK_ID, obj_len, (const unsigned char *)obj)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTDECODE, FAIL, "can't decode link")
 
     /* Compare the string values */
diff --git a/src/H5Gcache.c b/src/H5Gcache.c
index 1ca80df..994c5bf 100644
--- a/src/H5Gcache.c
+++ b/src/H5Gcache.c
@@ -103,49 +103,43 @@ H5FL_SEQ_EXTERN(H5G_entry_t);
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5G_node_load
+ * Function:    H5G_node_load
  *
- * Purpose:	Loads a symbol table node from the file.
+ * Purpose:     Loads a symbol table node from the file.
  *
- * Return:	Success:	Ptr to the new table.
+ * Return:      Success:    Ptr to the new table.
+ *              Failure:    NULL
  *
- *		Failure:	NULL
- *
- * Programmer:	Robb Matzke
- *		matzke@llnl.gov
- *		Jun 23 1997
+ * Programmer:  Robb Matzke
+ *              matzke@llnl.gov
+ *              Jun 23 1997
  *
  *-------------------------------------------------------------------------
  */
 static H5G_node_t *
 H5G_node_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *udata)
 {
-    H5G_node_t		   *sym = NULL;
-    H5WB_t                 *wb = NULL;     /* Wrapped buffer for node data */
-    uint8_t                 node_buf[H5G_NODE_BUF_SIZE]; /* Buffer for node */
-    uint8_t		   *node;           /* Pointer to node buffer */
+    H5G_node_t         *sym = NULL;
+    H5WB_t             *wb = NULL;                      /* Wrapped buffer for node data */
+    uint8_t             node_buf[H5G_NODE_BUF_SIZE];    /* Buffer for node */
+    uint8_t            *node;                           /* Pointer to node buffer */
     const uint8_t	   *p;
-    H5G_node_t		   *ret_value;	/*for error handling */
+    const uint8_t	   *p_end;
+    H5G_node_t         *ret_value;                      /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT
 
-    /*
-     * Check arguments.
-     */
+    /* Sanity checks */
     HDassert(f);
     HDassert(H5F_addr_defined(addr));
     HDassert(udata);
 
-    /*
-     * Initialize variables.
-     */
-
     /* Allocate symbol table data structures */
     if(NULL == (sym = H5FL_CALLOC(H5G_node_t)))
-	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
+        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
     sym->node_size = H5G_NODE_SIZE(f);
     if(NULL == (sym->entry = H5FL_SEQ_CALLOC(H5G_entry_t, (size_t)(2 * H5F_SYM_LEAF_K(f)))))
-	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
+        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
 
     /* Wrap the local buffer for serialized node info */
     if(NULL == (wb = H5WB_wrap(node_buf, sizeof(node_buf))))
@@ -157,19 +151,24 @@ H5G_node_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *udata)
 
     /* Read the serialized symbol table node. */
     if(H5F_block_read(f, H5FD_MEM_BTREE, addr, sym->node_size, dxpl_id, node) < 0)
-	HGOTO_ERROR(H5E_SYM, H5E_READERROR, NULL, "unable to read symbol table node")
+        HGOTO_ERROR(H5E_SYM, H5E_READERROR, NULL, "unable to read symbol table node")
 
     /* Get temporary pointer to serialized node */
     p = node;
 
+    /* Get a pointer to the end of the node. This ensures we don't run off
+     * the end of the buffer if the file is corrupt.
+     */
+    p_end = p + sym->node_size - 1;
+
     /* magic */
     if(HDmemcmp(p, H5G_NODE_MAGIC, (size_t)H5_SIZEOF_MAGIC))
-	HGOTO_ERROR(H5E_SYM, H5E_CANTLOAD, NULL, "bad symbol table node signature")
+        HGOTO_ERROR(H5E_SYM, H5E_CANTLOAD, NULL, "bad symbol table node signature")
     p += 4;
 
     /* version */
     if(H5G_NODE_VERS != *p++)
-	HGOTO_ERROR(H5E_SYM, H5E_CANTLOAD, NULL, "bad symbol table node version")
+        HGOTO_ERROR(H5E_SYM, H5E_CANTLOAD, NULL, "bad symbol table node version")
 
     /* reserved */
     p++;
@@ -178,8 +177,8 @@ H5G_node_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *udata)
     UINT16DECODE(p, sym->nsyms);
 
     /* entries */
-    if(H5G__ent_decode_vec(f, &p, sym->entry, sym->nsyms) < 0)
-	HGOTO_ERROR(H5E_SYM, H5E_CANTLOAD, NULL, "unable to decode symbol table entries")
+    if(H5G__ent_decode_vec(f, &p, p_end, sym->entry, sym->nsyms) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_CANTLOAD, NULL, "unable to decode symbol table entries")
 
     /* Set return value */
     ret_value = sym;
diff --git a/src/H5Gdense.c b/src/H5Gdense.c
index 9ec8951..a43939e 100644
--- a/src/H5Gdense.c
+++ b/src/H5Gdense.c
@@ -597,7 +597,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5G_dense_lookup_by_idx_fh_cb(const void *obj, size_t H5_ATTR_UNUSED obj_len, void *_udata)
+H5G_dense_lookup_by_idx_fh_cb(const void *obj, size_t obj_len, void *_udata)
 {
     H5G_fh_ud_lbi_t *udata = (H5G_fh_ud_lbi_t *)_udata;       /* User data for fractal heap 'op' callback */
     H5O_link_t *tmp_lnk = NULL;         /* Temporary pointer to link */
@@ -606,7 +606,7 @@ H5G_dense_lookup_by_idx_fh_cb(const void *obj, size_t H5_ATTR_UNUSED obj_len, vo
     FUNC_ENTER_NOAPI_NOINIT
 
     /* Decode link information & keep a copy */
-    if(NULL == (tmp_lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_LINK_ID, (const unsigned char *)obj)))
+    if(NULL == (tmp_lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_LINK_ID, obj_len, (const unsigned char *)obj)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTDECODE, FAIL, "can't decode link")
 
     /* Copy link information */
@@ -887,7 +887,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5G_dense_iterate_fh_cb(const void *obj, size_t H5_ATTR_UNUSED obj_len, void *_udata)
+H5G_dense_iterate_fh_cb(const void *obj, size_t obj_len, void *_udata)
 {
     H5G_fh_ud_it_t *udata = (H5G_fh_ud_it_t *)_udata;       /* User data for fractal heap 'op' callback */
     herr_t ret_value = SUCCEED;   /* Return value */
@@ -901,7 +901,7 @@ H5G_dense_iterate_fh_cb(const void *obj, size_t H5_ATTR_UNUSED obj_len, void *_u
      *  HDF5 routine, it could attempt to re-protect that direct block for the
      *  heap, causing the HDF5 routine called to fail - QAK)
      */
-    if(NULL == (udata->lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_LINK_ID, (const unsigned char *)obj)))
+    if(NULL == (udata->lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_LINK_ID, obj_len, (const unsigned char *)obj)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTDECODE, FAIL, "can't decode link")
 
 done:
@@ -1099,7 +1099,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5G_dense_get_name_by_idx_fh_cb(const void *obj, size_t H5_ATTR_UNUSED obj_len, void *_udata)
+H5G_dense_get_name_by_idx_fh_cb(const void *obj, size_t obj_len, void *_udata)
 {
     H5G_fh_ud_gnbi_t *udata = (H5G_fh_ud_gnbi_t *)_udata;       /* User data for fractal heap 'op' callback */
     H5O_link_t *lnk;            /* Pointer to link created from heap object */
@@ -1108,7 +1108,7 @@ H5G_dense_get_name_by_idx_fh_cb(const void *obj, size_t H5_ATTR_UNUSED obj_len,
     FUNC_ENTER_NOAPI_NOINIT
 
     /* Decode link information */
-    if(NULL == (lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_LINK_ID, (const unsigned char *)obj)))
+    if(NULL == (lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_LINK_ID, obj_len, (const unsigned char *)obj)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTDECODE, FAIL, "can't decode link")
 
     /* Get the length of the name */
@@ -1306,7 +1306,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5G_dense_remove_fh_cb(const void *obj, size_t H5_ATTR_UNUSED obj_len, void *_udata)
+H5G_dense_remove_fh_cb(const void *obj, size_t obj_len, void *_udata)
 {
     H5G_fh_ud_rm_t *udata = (H5G_fh_ud_rm_t *)_udata;       /* User data for fractal heap 'op' callback */
     H5O_link_t *lnk = NULL;             /* Pointer to link created from heap object */
@@ -1316,7 +1316,7 @@ H5G_dense_remove_fh_cb(const void *obj, size_t H5_ATTR_UNUSED obj_len, void *_ud
     FUNC_ENTER_NOAPI_NOINIT
 
     /* Decode link information */
-    if(NULL == (lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_LINK_ID, (const unsigned char *)obj)))
+    if(NULL == (lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_LINK_ID, obj_len, (const unsigned char *)obj)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTDECODE, FAIL, "can't decode link")
 
     /* Check for removing the link from the creation order index */
@@ -1483,7 +1483,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5G_dense_remove_by_idx_fh_cb(const void *obj, size_t H5_ATTR_UNUSED obj_len, void *_udata)
+H5G_dense_remove_by_idx_fh_cb(const void *obj, size_t obj_len, void *_udata)
 {
     H5G_fh_ud_rmbi_t *udata = (H5G_fh_ud_rmbi_t *)_udata;       /* User data for fractal heap 'op' callback */
     herr_t ret_value = SUCCEED; /* Return value */
@@ -1491,7 +1491,7 @@ H5G_dense_remove_by_idx_fh_cb(const void *obj, size_t H5_ATTR_UNUSED obj_len, vo
     FUNC_ENTER_NOAPI_NOINIT
 
     /* Decode link information */
-    if(NULL == (udata->lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_LINK_ID, (const unsigned char *)obj)))
+    if(NULL == (udata->lnk = (H5O_link_t *)H5O_msg_decode(udata->f, udata->dxpl_id, NULL, H5O_LINK_ID, obj_len, (const unsigned char *)obj)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTDECODE, H5_ITER_ERROR, "can't decode link")
 
     /* Can't operate on link here because the fractal heap block is locked */
diff --git a/src/H5Gent.c b/src/H5Gent.c
index bb6aa38..1bd8e63 100644
--- a/src/H5Gent.c
+++ b/src/H5Gent.c
@@ -91,7 +91,8 @@ H5FL_BLK_EXTERN(str_buf);
  *-------------------------------------------------------------------------
  */
 herr_t
-H5G__ent_decode_vec(const H5F_t *f, const uint8_t **pp, H5G_entry_t *ent, unsigned n)
+H5G__ent_decode_vec(const H5F_t *f, const uint8_t **pp, const uint8_t *p_end,
+        H5G_entry_t *ent, unsigned n)
 {
     unsigned    u;                      /* Local index variable */
     herr_t      ret_value = SUCCEED;    /* Return value */
@@ -104,9 +105,12 @@ H5G__ent_decode_vec(const H5F_t *f, const uint8_t **pp, H5G_entry_t *ent, unsign
     HDassert(ent);
 
     /* decode entries */
-    for(u = 0; u < n; u++)
+    for(u = 0; u < n; u++) {
+        if(*pp > p_end)
+            HGOTO_ERROR(H5E_SYM, H5E_CANTDECODE, FAIL, "ran off the end of the buffer")
         if(H5G_ent_decode(f, pp, ent + u) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTDECODE, FAIL, "can't decode")
+    }
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
diff --git a/src/H5Gpkg.h b/src/H5Gpkg.h
index 07aff02..f49ef26 100644
--- a/src/H5Gpkg.h
+++ b/src/H5Gpkg.h
@@ -1,4 +1,4 @@
-/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
  * Copyright by The HDF Group.                                               *
  * Copyright by the Board of Trustees of the University of Illinois.         *
  * All rights reserved.                                                      *
@@ -400,9 +400,9 @@ H5_DLL void H5G__ent_copy(H5G_entry_t *dst, const H5G_entry_t *src,
             H5_copy_depth_t depth);
 H5_DLL void H5G__ent_reset(H5G_entry_t *ent);
 H5_DLL herr_t H5G__ent_decode_vec(const H5F_t *f, const uint8_t **pp,
-				  H5G_entry_t *ent, unsigned n);
+				    const uint8_t *p_end, H5G_entry_t *ent, unsigned n);
 H5_DLL herr_t H5G__ent_encode_vec(const H5F_t *f, uint8_t **pp,
-				  const H5G_entry_t *ent, unsigned n);
+                    const H5G_entry_t *ent, unsigned n);
 H5_DLL herr_t H5G__ent_convert(H5F_t *f, hid_t dxpl_id, H5HL_t *heap,
     const char *name, const H5O_link_t *lnk, H5O_type_t obj_type,
     const void *crt_info, H5G_entry_t *ent);
diff --git a/src/H5HFcache.c b/src/H5HFcache.c
index f0d251c..0d25dbf 100644
--- a/src/H5HFcache.c
+++ b/src/H5HFcache.c
@@ -384,7 +384,7 @@ H5HF_cache_hdr_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
         UINT32DECODE(p, hdr->pline_root_direct_filter_mask);
 
         /* Decode I/O filter information */
-        if(NULL == (pline = (H5O_pline_t *)H5O_msg_decode(hdr->f, udata->dxpl_id, NULL, H5O_PLINE_ID, p)))
+        if(NULL == (pline = (H5O_pline_t *)H5O_msg_decode(hdr->f, udata->dxpl_id, NULL, H5O_PLINE_ID, hdr->filter_len, p)))
             HGOTO_ERROR(H5E_HEAP, H5E_CANTDECODE, NULL, "can't decode I/O pipeline filters")
         p += hdr->filter_len;
 
diff --git a/src/H5Oainfo.c b/src/H5Oainfo.c
index e85df44..5aab4c6 100644
--- a/src/H5Oainfo.c
+++ b/src/H5Oainfo.c
@@ -34,7 +34,7 @@
 
 /* PRIVATE PROTOTYPES */
 static void *H5O_ainfo_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_ainfo_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_ainfo_copy(const void *_mesg, void *_dest);
 static size_t H5O_ainfo_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -104,7 +104,8 @@ H5FL_DEFINE_STATIC(H5O_ainfo_t);
  */
 static void *
 H5O_ainfo_decode(H5F_t *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5O_ainfo_t	*ainfo = NULL;  /* Attribute info */
     unsigned char flags;        /* Flags for encoding attribute info */
diff --git a/src/H5Oattr.c b/src/H5Oattr.c
index 149f04a..c2c0fe3 100644
--- a/src/H5Oattr.c
+++ b/src/H5Oattr.c
@@ -26,7 +26,7 @@
 /* PRIVATE PROTOTYPES */
 static herr_t H5O_attr_encode(H5F_t *f, uint8_t *p, const void *mesg);
 static void *H5O_attr_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static void *H5O_attr_copy(const void *_mesg, void *_dest);
 static size_t H5O_attr_size(const H5F_t *f, const void *_mesg);
 static herr_t H5O_attr_free(void *mesg);
@@ -121,7 +121,7 @@ H5FL_EXTERN(H5S_extent_t);
 --------------------------------------------------------------------------*/
 static void *
 H5O_attr_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, unsigned H5_ATTR_UNUSED mesg_flags,
-    unsigned *ioflags, const uint8_t *p)
+    unsigned *ioflags, size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5A_t		*attr = NULL;
     H5S_extent_t	*extent;	/*extent dimensionality information  */
@@ -182,7 +182,7 @@ H5O_attr_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, unsigned H5_ATTR_UNUSED
 
     /* Decode the attribute's datatype */
     if(NULL == (attr->shared->dt = (H5T_t *)(H5O_MSG_DTYPE->decode)(f, dxpl_id, open_oh,
-        ((flags & H5O_ATTR_FLAG_TYPE_SHARED) ? H5O_MSG_FLAG_SHARED : 0), ioflags, p)))
+        ((flags & H5O_ATTR_FLAG_TYPE_SHARED) ? H5O_MSG_FLAG_SHARED : 0), ioflags, attr->shared->dt_size, p)))
         HGOTO_ERROR(H5E_ATTR, H5E_CANTDECODE, NULL, "can't decode attribute datatype")
     if(attr->shared->version < H5O_ATTR_VERSION_2)
         p += H5O_ALIGN_OLD(attr->shared->dt_size);
@@ -197,7 +197,7 @@ H5O_attr_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, unsigned H5_ATTR_UNUSED
 
     /* Decode attribute's dataspace extent */
     if((extent = (H5S_extent_t *)(H5O_MSG_SDSPACE->decode)(f, dxpl_id, open_oh,
-        ((flags & H5O_ATTR_FLAG_SPACE_SHARED) ? H5O_MSG_FLAG_SHARED : 0), ioflags, p)) == NULL)
+            ((flags & H5O_ATTR_FLAG_SPACE_SHARED) ? H5O_MSG_FLAG_SHARED : 0), ioflags, attr->shared->ds_size, p)) == NULL)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTDECODE, NULL, "can't decode attribute dataspace")
 
     /* Copy the extent information to the dataspace */
diff --git a/src/H5Obogus.c b/src/H5Obogus.c
index 7a058b2..ba9a8ad 100644
--- a/src/H5Obogus.c
+++ b/src/H5Obogus.c
@@ -37,7 +37,7 @@
 
 /* PRIVATE PROTOTYPES */
 static void *H5O_bogus_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_bogus_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static size_t H5O_bogus_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
 static herr_t H5O_bogus_debug(H5F_t *f, hid_t dxpl_id, const void *_mesg, FILE * stream,
@@ -110,7 +110,8 @@ const H5O_msg_class_t H5O_MSG_BOGUS_INVALID[1] = {{
  */
 static void *
 H5O_bogus_decode(H5F_t *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5O_bogus_t *mesg = NULL;
     void *ret_value;            /* Return value */
diff --git a/src/H5Obtreek.c b/src/H5Obtreek.c
index 70aacc7..6bcdcc3 100644
--- a/src/H5Obtreek.c
+++ b/src/H5Obtreek.c
@@ -27,7 +27,7 @@
 #include "H5MMprivate.h"	/* Memory management			*/
 
 static void  *H5O_btreek_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_btreek_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void  *H5O_btreek_copy(const void *_mesg, void *_dest);
 static size_t H5O_btreek_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -78,7 +78,8 @@ const H5O_msg_class_t H5O_MSG_BTREEK[1] = {{
  */
 static void *
 H5O_btreek_decode(H5F_t H5_ATTR_UNUSED *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5O_btreek_t	*mesg;          /* Native message */
     void                *ret_value;     /* Return value */
diff --git a/src/H5Ocache.c b/src/H5Ocache.c
index ebae3f5..39f3ca3 100644
--- a/src/H5Ocache.c
+++ b/src/H5Ocache.c
@@ -1288,7 +1288,7 @@ H5O_chunk_deserialize(H5O_t *oh, haddr_t addr, size_t len, const uint8_t *image,
             unsigned ioflags = 0;   /* Flags for decode routine */
 
             /* Decode continuation message */
-            cont = (H5O_cont_t *)(H5O_MSG_CONT->decode)(udata->f, udata->dxpl_id, NULL, 0, &ioflags, oh->mesg[curmesg].raw);
+            cont = (H5O_cont_t *)(H5O_MSG_CONT->decode)(udata->f, udata->dxpl_id, NULL, 0, &ioflags, oh->mesg[curmesg].raw_size, oh->mesg[curmesg].raw);
             cont->chunkno = udata->cont_msg_info->nmsgs + 1;	/*the next continuation message/chunk */
 
             /* Save 'native' form of continuation message */
@@ -1312,7 +1312,7 @@ H5O_chunk_deserialize(H5O_t *oh, haddr_t addr, size_t len, const uint8_t *image,
 
             /* Decode ref. count message */
             HDassert(oh->version > H5O_VERSION_1);
-            refcount = (H5O_refcount_t *)(H5O_MSG_REFCOUNT->decode)(udata->f, udata->dxpl_id, NULL, 0, &ioflags, oh->mesg[curmesg].raw);
+            refcount = (H5O_refcount_t *)(H5O_MSG_REFCOUNT->decode)(udata->f, udata->dxpl_id, NULL, 0, &ioflags, oh->mesg[curmesg].raw_size, oh->mesg[curmesg].raw);
 
             /* Save 'native' form of ref. count message */
             oh->mesg[curmesg].native = refcount;
diff --git a/src/H5Ocont.c b/src/H5Ocont.c
index 681f54a..b91b181 100644
--- a/src/H5Ocont.c
+++ b/src/H5Ocont.c
@@ -36,7 +36,7 @@
 
 /* PRIVATE PROTOTYPES */
 static void *H5O_cont_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_cont_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static size_t H5O_cont_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
 static herr_t H5O_cont_free(void *mesg);
@@ -89,7 +89,8 @@ H5FL_DEFINE(H5O_cont_t);
  */
 static void *
 H5O_cont_decode(H5F_t *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5O_cont_t             *cont = NULL;
     void                   *ret_value;
diff --git a/src/H5Odrvinfo.c b/src/H5Odrvinfo.c
index 6f715f8..fd8ad6b 100644
--- a/src/H5Odrvinfo.c
+++ b/src/H5Odrvinfo.c
@@ -27,7 +27,7 @@
 #include "H5MMprivate.h"	/* Memory management			*/
 
 static void  *H5O_drvinfo_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_drvinfo_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void  *H5O_drvinfo_copy(const void *_mesg, void *_dest);
 static size_t H5O_drvinfo_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -79,7 +79,8 @@ const H5O_msg_class_t H5O_MSG_DRVINFO[1] = {{
  */
 static void *
 H5O_drvinfo_decode(H5F_t H5_ATTR_UNUSED *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5O_drvinfo_t	*mesg;          /* Native message */
     void                *ret_value;     /* Return value */
diff --git a/src/H5Odtype.c b/src/H5Odtype.c
index 774b071..85fbef4 100644
--- a/src/H5Odtype.c
+++ b/src/H5Odtype.c
@@ -29,7 +29,7 @@
 /* PRIVATE PROTOTYPES */
 static herr_t H5O_dtype_encode(H5F_t *f, uint8_t *p, const void *mesg);
 static void *H5O_dtype_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static void *H5O_dtype_copy(const void *_mesg, void *_dest);
 static size_t H5O_dtype_size(const H5F_t *f, const void *_mesg);
 static herr_t H5O_dtype_reset(void *_mesg);
@@ -1093,7 +1093,7 @@ done:
 --------------------------------------------------------------------------*/
 static void *
 H5O_dtype_decode(H5F_t *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh, unsigned H5_ATTR_UNUSED mesg_flags,
-    unsigned *ioflags/*in,out*/, const uint8_t *p)
+    unsigned *ioflags/*in,out*/, size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5T_t	*dt = NULL;
     void        *ret_value;     /* Return value */
diff --git a/src/H5Oefl.c b/src/H5Oefl.c
index 218d250..546eb4f 100644
--- a/src/H5Oefl.c
+++ b/src/H5Oefl.c
@@ -28,7 +28,7 @@
 
 /* PRIVATE PROTOTYPES */
 static void *H5O_efl_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_efl_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_efl_copy(const void *_mesg, void *_dest);
 static size_t H5O_efl_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -88,7 +88,8 @@ const H5O_msg_class_t H5O_MSG_EFL[1] = {{
  */
 static void *
 H5O_efl_decode(H5F_t *f, hid_t dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5O_efl_t   *mesg = NULL;
     int         version;
diff --git a/src/H5Ofill.c b/src/H5Ofill.c
index 721c648..70704c5 100644
--- a/src/H5Ofill.c
+++ b/src/H5Ofill.c
@@ -32,11 +32,11 @@
 
 
 static void  *H5O_fill_old_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_fill_old_encode(H5F_t *f, uint8_t *p, const void *_mesg);
 static size_t H5O_fill_old_size(const H5F_t *f, const void *_mesg);
 static void  *H5O_fill_new_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_fill_new_encode(H5F_t *f, uint8_t *p, const void *_mesg);
 static size_t H5O_fill_new_size(const H5F_t *f, const void *_mesg);
 static void  *H5O_fill_copy(const void *_mesg, void *_dest);
@@ -183,7 +183,8 @@ H5FL_BLK_EXTERN(type_conv);
  */
 static void *
 H5O_fill_new_decode(H5F_t H5_ATTR_UNUSED *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5O_fill_t	*fill = NULL;
     void	*ret_value;
@@ -297,7 +298,8 @@ done:
  */
 static void *
 H5O_fill_old_decode(H5F_t H5_ATTR_UNUSED *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5O_fill_t *fill = NULL;		/* Decoded fill value message */
     void *ret_value;                    /* Return value */
diff --git a/src/H5Oginfo.c b/src/H5Oginfo.c
index d8be51f..8ba1f71 100644
--- a/src/H5Oginfo.c
+++ b/src/H5Oginfo.c
@@ -32,7 +32,7 @@
 
 /* PRIVATE PROTOTYPES */
 static void *H5O_ginfo_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_ginfo_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_ginfo_copy(const void *_mesg, void *_dest);
 static size_t H5O_ginfo_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -94,7 +94,8 @@ H5FL_DEFINE_STATIC(H5O_ginfo_t);
  */
 static void *
 H5O_ginfo_decode(H5F_t H5_ATTR_UNUSED *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5O_ginfo_t         *ginfo = NULL;  /* Pointer to group information message */
     unsigned char       flags;          /* Flags for encoding group info */
diff --git a/src/H5Olayout.c b/src/H5Olayout.c
index 17385c2..3f5076c 100644
--- a/src/H5Olayout.c
+++ b/src/H5Olayout.c
@@ -35,7 +35,7 @@
 
 /* PRIVATE PROTOTYPES */
 static void *H5O_layout_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_layout_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_layout_copy(const void *_mesg, void *_dest);
 static size_t H5O_layout_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -95,7 +95,8 @@ H5FL_DEFINE(H5O_layout_t);
  */
 static void *
 H5O_layout_decode(H5F_t *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5O_layout_t           *mesg = NULL;
     unsigned               u;
diff --git a/src/H5Olinfo.c b/src/H5Olinfo.c
index 03e545f..a612ae5 100644
--- a/src/H5Olinfo.c
+++ b/src/H5Olinfo.c
@@ -36,7 +36,7 @@
 
 /* PRIVATE PROTOTYPES */
 static void *H5O_linfo_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_linfo_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_linfo_copy(const void *_mesg, void *_dest);
 static size_t H5O_linfo_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -113,7 +113,8 @@ H5FL_DEFINE_STATIC(H5O_linfo_t);
  */
 static void *
 H5O_linfo_decode(H5F_t *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5O_linfo_t	*linfo = NULL;  /* Link info */
     unsigned char index_flags;  /* Flags for encoding link index info */
diff --git a/src/H5Olink.c b/src/H5Olink.c
index 1b57f22..c0dd1d8 100644
--- a/src/H5Olink.c
+++ b/src/H5Olink.c
@@ -38,7 +38,7 @@
 
 /* PRIVATE PROTOTYPES */
 static void *H5O_link_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_link_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_link_copy(const void *_mesg, void *_dest);
 static size_t H5O_link_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -117,7 +117,8 @@ H5FL_DEFINE_STATIC(H5O_link_t);
  */
 static void *
 H5O_link_decode(H5F_t *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5O_link_t          *lnk = NULL;    /* Pointer to link message */
     size_t              len = 0;        /* Length of a string in the message */
diff --git a/src/H5Omessage.c b/src/H5Omessage.c
index b6d2876..a2e4e88 100644
--- a/src/H5Omessage.c
+++ b/src/H5Omessage.c
@@ -1821,7 +1821,7 @@ done:
  */
 void *
 H5O_msg_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, unsigned type_id,
-    const unsigned char *buf)
+    size_t buf_size, const unsigned char *buf)
 {
     const H5O_msg_class_t   *type;      /* Actual H5O class type for the ID */
     void *ret_value;                    /* Return value */
@@ -1836,7 +1836,7 @@ H5O_msg_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, unsigned type_id,
     HDassert(type);
 
     /* decode */
-    if((ret_value = (type->decode)(f, dxpl_id, open_oh, 0, &ioflags, buf)) == NULL)
+    if((ret_value = (type->decode)(f, dxpl_id, open_oh, 0, &ioflags, buf_size, buf)) == NULL)
         HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, NULL, "unable to decode message")
 
 done:
diff --git a/src/H5Omtime.c b/src/H5Omtime.c
index 46dd499..e4db09b 100644
--- a/src/H5Omtime.c
+++ b/src/H5Omtime.c
@@ -27,12 +27,12 @@
 
 
 static void *H5O_mtime_new_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_mtime_new_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static size_t H5O_mtime_new_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
 
 static void *H5O_mtime_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_mtime_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_mtime_copy(const void *_mesg, void *_dest);
 static size_t H5O_mtime_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -118,7 +118,8 @@ H5FL_DEFINE(time_t);
  */
 static void *
 H5O_mtime_new_decode(H5F_t H5_ATTR_UNUSED *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     time_t	*mesg;
     uint32_t    tmp_time;       /* Temporary copy of the time */
@@ -171,7 +172,8 @@ done:
  */
 static void *
 H5O_mtime_decode(H5F_t H5_ATTR_UNUSED *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     time_t	*mesg, the_time;
     int	i;
diff --git a/src/H5Oname.c b/src/H5Oname.c
index 007e20f..5248168 100644
--- a/src/H5Oname.c
+++ b/src/H5Oname.c
@@ -32,7 +32,7 @@
 
 /* PRIVATE PROTOTYPES */
 static void *H5O_name_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_name_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_name_copy(const void *_mesg, void *_dest);
 static size_t H5O_name_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -83,7 +83,8 @@ const H5O_msg_class_t H5O_MSG_NAME[1] = {{
  */
 static void *
 H5O_name_decode(H5F_t H5_ATTR_UNUSED *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5O_name_t          *mesg;
     void                *ret_value;     /* Return value */
diff --git a/src/H5Opkg.h b/src/H5Opkg.h
index cd585be..f4b8014 100644
--- a/src/H5Opkg.h
+++ b/src/H5Opkg.h
@@ -186,7 +186,7 @@
                                                                               \
         /* Decode the message */                                              \
         HDassert(msg_type->decode);                                           \
-        if(NULL == ((MSG)->native = (msg_type->decode)((F), (DXPL), (OH), (MSG)->flags, &ioflags, (MSG)->raw))) \
+        if(NULL == ((MSG)->native = (msg_type->decode)((F), (DXPL), (OH), (MSG)->flags, &ioflags, (MSG)->raw_size, (MSG)->raw))) \
             HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, ERR, "unable to decode message") \
                                                                               \
         /* Mark the message dirty if it was changed by decoding */            \
@@ -222,7 +222,7 @@ struct H5O_msg_class_t {
     const char	*name;				/*for debugging             */
     size_t	native_size;			/*size of native message    */
     unsigned    share_flags;			/* Message sharing settings */
-    void	*(*decode)(H5F_t *, hid_t, H5O_t *, unsigned, unsigned *, const uint8_t *);
+    void	*(*decode)(H5F_t *, hid_t, H5O_t *, unsigned, unsigned *, size_t, const uint8_t *);
     herr_t	(*encode)(H5F_t *, hbool_t, uint8_t *, const void *);
     void	*(*copy)(const void *, void *);	/*copy native value         */
     size_t	(*raw_size)(const H5F_t *, hbool_t, const void *);/*sizeof encoded message	*/
diff --git a/src/H5Opline.c b/src/H5Opline.c
index fb08431..adaee33 100644
--- a/src/H5Opline.c
+++ b/src/H5Opline.c
@@ -33,7 +33,7 @@
 /* PRIVATE PROTOTYPES */
 static herr_t H5O_pline_encode(H5F_t *f, uint8_t *p, const void *mesg);
 static void *H5O_pline_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static void *H5O_pline_copy(const void *_mesg, void *_dest);
 static size_t H5O_pline_size(const H5F_t *f, const void *_mesg);
 static herr_t H5O_pline_reset(void *_mesg);
@@ -108,13 +108,15 @@ H5FL_DEFINE(H5O_pline_t);
  */
 static void *
 H5O_pline_decode(H5F_t H5_ATTR_UNUSED *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t p_size, const uint8_t *p)
 {
     H5O_pline_t		*pline = NULL;          /* Pipeline message */
     H5Z_filter_info_t   *filter;                /* Filter to decode */
     size_t		name_length;            /* Length of filter name */
     size_t		i;                      /* Local index variable */
-    void		*ret_value;             /* Return value */
+    const uint8_t *p_end = p + p_size - 1;  /* End of the p buffer */
+    void		*ret_value = NULL;      /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT
 
@@ -123,12 +125,12 @@ H5O_pline_decode(H5F_t H5_ATTR_UNUSED *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5
 
     /* Allocate space for I/O pipeline message */
     if(NULL == (pline = H5FL_CALLOC(H5O_pline_t)))
-	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
+        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
 
     /* Version */
     pline->version = *p++;
     if(pline->version < H5O_PLINE_VERSION_1 || pline->version > H5O_PLINE_VERSION_LATEST)
-	HGOTO_ERROR(H5E_PLINE, H5E_CANTLOAD, NULL, "bad version number for filter pipeline message")
+        HGOTO_ERROR(H5E_PLINE, H5E_CANTLOAD, NULL, "bad version number for filter pipeline message")
 
     /* Number of filters */
     pline->nused = *p++;
@@ -149,12 +151,12 @@ H5O_pline_decode(H5F_t H5_ATTR_UNUSED *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5
     /* Allocate array for filters */
     pline->nalloc = pline->nused;
     if(NULL == (pline->filter = (H5Z_filter_info_t *)H5MM_calloc(pline->nalloc * sizeof(pline->filter[0]))))
-	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
+        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
 
     /* Decode filters */
     for(i = 0, filter = &pline->filter[0]; i < pline->nused; i++, filter++) {
         /* Filter ID */
-	UINT16DECODE(p, filter->id);
+        UINT16DECODE(p, filter->id);
 
         /* Length of filter name */
         if(pline->version > H5O_PLINE_VERSION_1 && filter->id < H5Z_FILTER_RESERVED)
@@ -166,18 +168,18 @@ H5O_pline_decode(H5F_t H5_ATTR_UNUSED *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5
         } /* end if */
 
         /* Filter flags */
-	UINT16DECODE(p, filter->flags);
+        UINT16DECODE(p, filter->flags);
 
         /* Number of filter parameters ("client data elements") */
-	UINT16DECODE(p, filter->cd_nelmts);
+        UINT16DECODE(p, filter->cd_nelmts);
 
         /* Filter name, if there is one */
-	if(name_length) {
+        if(name_length) {
             size_t actual_name_length;          /* Actual length of name */
 
             /* Determine actual name length (without padding, but with null terminator) */
-	    actual_name_length = HDstrlen((const char *)p) + 1;
-	    HDassert(actual_name_length <= name_length);
+            actual_name_length = HDstrlen((const char *)p) + 1;
+            HDassert(actual_name_length <= name_length);
 
             /* Allocate space for the filter name, or use the internal buffer */
             if(actual_name_length > H5Z_COMMON_NAME_LEN) {
@@ -188,12 +190,12 @@ H5O_pline_decode(H5F_t H5_ATTR_UNUSED *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5
             else
                 filter->name = filter->_name;
 
-	    HDstrncpy(filter->name, (const char *)p, actual_name_length);
-	    p += name_length;
-	} /* end if */
+            HDstrncpy(filter->name, (const char *)p, actual_name_length);
+            p += name_length;
+        } /* end if */
 
         /* Filter parameters */
-	if(filter->cd_nelmts) {
+        if(filter->cd_nelmts) {
             size_t	j;              /* Local index variable */
 
             /* Allocate space for the client data elements, or use the internal buffer */
@@ -205,15 +207,20 @@ H5O_pline_decode(H5F_t H5_ATTR_UNUSED *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5
             else
                 filter->cd_values = filter->_cd_values;
 
-	    /*
-	     * Read the client data values and the padding
-	     */
-	    for(j = 0; j < filter->cd_nelmts; j++)
-		UINT32DECODE(p, filter->cd_values[j]);
+            /*
+             * Read the client data values and the padding
+             */
+            for (j = 0; j < filter->cd_nelmts; j++) {
+                if (p + 4 - 1 <= p_end)
+                    UINT32DECODE(p, filter->cd_values[j])
+                else
+                    HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "ran off the end of the buffer: current p = %p, p_size = %zu, p_end = %p", p, p_size, p_end)
+            }
+
             if(pline->version == H5O_PLINE_VERSION_1)
                 if(filter->cd_nelmts % 2)
                     p += 4; /*padding*/
-	} /* end if */
+        } /* end if */
     } /* end for */
 
     /* Set return value */
diff --git a/src/H5Oprivate.h b/src/H5Oprivate.h
index ca0fc8e..1f51705 100644
--- a/src/H5Oprivate.h
+++ b/src/H5Oprivate.h
@@ -710,7 +710,7 @@ H5_DLL herr_t H5O_msg_get_crt_index(unsigned type_id, const void *mesg,
 H5_DLL herr_t H5O_msg_encode(H5F_t *f, unsigned type_id, hbool_t disable_shared,
     unsigned char *buf, const void *obj);
 H5_DLL void* H5O_msg_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned type_id, const unsigned char *buf);
+    unsigned type_id, size_t buf_size, const unsigned char *buf);
 H5_DLL herr_t H5O_msg_delete(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
     unsigned type_id, void *mesg);
 H5_DLL int H5O_msg_get_chunkno(const H5O_loc_t *loc, unsigned type_id, hid_t dxpl_id);
diff --git a/src/H5Orefcount.c b/src/H5Orefcount.c
index 22b1a02..78ff791 100644
--- a/src/H5Orefcount.c
+++ b/src/H5Orefcount.c
@@ -32,7 +32,7 @@
 
 /* PRIVATE PROTOTYPES */
 static void *H5O_refcount_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_refcount_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_refcount_copy(const void *_mesg, void *_dest);
 static size_t H5O_refcount_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -89,7 +89,8 @@ H5FL_DEFINE_STATIC(H5O_refcount_t);
  */
 static void *
 H5O_refcount_decode(H5F_t H5_ATTR_UNUSED *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5O_refcount_t *refcount = NULL;  /* Reference count */
     void        *ret_value;     /* Return value */
diff --git a/src/H5Osdspace.c b/src/H5Osdspace.c
index 557a44b..627ea19 100644
--- a/src/H5Osdspace.c
+++ b/src/H5Osdspace.c
@@ -26,7 +26,7 @@
 
 /* PRIVATE PROTOTYPES */
 static void *H5O_sdspace_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_sdspace_encode(H5F_t *f, uint8_t *p, const void *_mesg);
 static void *H5O_sdspace_copy(const void *_mesg, void *_dest);
 static size_t H5O_sdspace_size(const H5F_t *f, const void *_mesg);
@@ -110,7 +110,8 @@ H5FL_ARR_EXTERN(hsize_t);
 --------------------------------------------------------------------------*/
 static void *
 H5O_sdspace_decode(H5F_t *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5S_extent_t	*sdim = NULL;/* New extent dimensionality structure */
     void		*ret_value;
diff --git a/src/H5Oshared.c b/src/H5Oshared.c
index 0d692f9..2475dd5 100644
--- a/src/H5Oshared.c
+++ b/src/H5Oshared.c
@@ -156,7 +156,7 @@ H5O_shared_read(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, unsigned *ioflags,
             HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, NULL, "can't read message from fractal heap.")
 
         /* Decode the message */
-        if(NULL == (ret_value = (type->decode)(f, dxpl_id, open_oh, 0, ioflags, mesg_ptr)))
+        if(NULL == (ret_value = (type->decode)(f, dxpl_id, open_oh, 0, ioflags, mesg_size, mesg_ptr)))
             HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, NULL, "can't decode shared message.")
     } /* end if */
     else {
diff --git a/src/H5Oshared.h b/src/H5Oshared.h
index f71f5f6..e60d7ba 100644
--- a/src/H5Oshared.h
+++ b/src/H5Oshared.h
@@ -47,7 +47,7 @@
  */
 static H5_INLINE void *
 H5O_SHARED_DECODE(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, unsigned mesg_flags,
-    unsigned *ioflags, const uint8_t *p)
+    unsigned *ioflags, size_t p_size, const uint8_t *p)
 {
     void *ret_value;            /* Return value */
 
@@ -67,7 +67,7 @@ H5O_SHARED_DECODE(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, unsigned mesg_flags,
     if(mesg_flags & H5O_MSG_FLAG_SHARED) {
         /* Retrieve native message info indirectly through shared message */
         if(NULL == (ret_value = H5O_shared_decode(f, dxpl_id, open_oh, ioflags, p, H5O_SHARED_TYPE)))
-	    HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, NULL, "unable to decode shared message")
+            HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, NULL, "unable to decode shared message")
 
         /* We currently do not support automatically fixing shared messages */
 #ifdef H5_STRICT_FORMAT_CHECKS
@@ -79,8 +79,8 @@ H5O_SHARED_DECODE(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, unsigned mesg_flags,
     } /* end if */
     else {
         /* Decode native message directly */
-        if(NULL == (ret_value = H5O_SHARED_DECODE_REAL(f, dxpl_id, open_oh, mesg_flags, ioflags, p)))
-	    HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, NULL, "unable to decode native message")
+        if(NULL == (ret_value = H5O_SHARED_DECODE_REAL(f, dxpl_id, open_oh, mesg_flags, ioflags, p_size, p)))
+            HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, NULL, "unable to decode native message")
     } /* end else */
 
 done:
diff --git a/src/H5Oshmesg.c b/src/H5Oshmesg.c
index 536f67e..489114a 100644
--- a/src/H5Oshmesg.c
+++ b/src/H5Oshmesg.c
@@ -27,7 +27,7 @@
 #include "H5MMprivate.h"	/* Memory management			*/
 
 static void  *H5O_shmesg_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_shmesg_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void  *H5O_shmesg_copy(const void *_mesg, void *_dest);
 static size_t H5O_shmesg_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -75,7 +75,8 @@ const H5O_msg_class_t H5O_MSG_SHMESG[1] = {{
  */
 static void *
 H5O_shmesg_decode(H5F_t *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5O_shmesg_table_t	*mesg;          /* Native message */
     void                *ret_value;     /* Return value */
diff --git a/src/H5Ostab.c b/src/H5Ostab.c
index 928307e..cf8c96a 100644
--- a/src/H5Ostab.c
+++ b/src/H5Ostab.c
@@ -35,7 +35,7 @@
 
 /* PRIVATE PROTOTYPES */
 static void *H5O_stab_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
-    unsigned mesg_flags, unsigned *ioflags, const uint8_t *p);
+    unsigned mesg_flags, unsigned *ioflags, size_t p_size, const uint8_t *p);
 static herr_t H5O_stab_encode(H5F_t *f, hbool_t disable_shared, uint8_t *p, const void *_mesg);
 static void *H5O_stab_copy(const void *_mesg, void *_dest);
 static size_t H5O_stab_size(const H5F_t *f, hbool_t disable_shared, const void *_mesg);
@@ -96,7 +96,8 @@ H5FL_DEFINE_STATIC(H5O_stab_t);
  */
 static void *
 H5O_stab_decode(H5F_t *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5_ATTR_UNUSED *open_oh,
-    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags, const uint8_t *p)
+    unsigned H5_ATTR_UNUSED mesg_flags, unsigned H5_ATTR_UNUSED *ioflags,
+    size_t H5_ATTR_UNUSED p_size, const uint8_t *p)
 {
     H5O_stab_t          *stab = NULL;
     void                *ret_value;     /* Return value */
diff --git a/src/H5S.c b/src/H5S.c
index d03d523..50bee52 100644
--- a/src/H5S.c
+++ b/src/H5S.c
@@ -1644,7 +1644,7 @@ H5S_decode(const unsigned char *buf)
 
     /* Decode the extent part of dataspace */
     /* (pass mostly bogus file pointer and bogus DXPL) */
-    if((extent = (H5S_extent_t *)H5O_msg_decode(f, H5P_DEFAULT, NULL, H5O_SDSPACE_ID, buf))==NULL)
+    if((extent = (H5S_extent_t *)H5O_msg_decode(f, H5P_DEFAULT, NULL, H5O_SDSPACE_ID, extent_size, buf))==NULL)
 	HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDECODE, NULL, "can't decode object")
     buf += extent_size;
 
diff --git a/src/H5SM.c b/src/H5SM.c
index 080eb7c..b549b59 100644
--- a/src/H5SM.c
+++ b/src/H5SM.c
@@ -69,7 +69,7 @@ static herr_t H5SM_write_mesg(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
 static herr_t H5SM_decr_ref(void *record, void *op_data, hbool_t *changed);
 static herr_t H5SM_delete_from_index(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
     H5SM_index_header_t *header, const H5O_shared_t * mesg,
-    unsigned *cache_flags, void ** /*out*/ encoded_mesg);
+    unsigned *cache_flags, size_t * /*out*/ mesg_size, void ** /*out*/ encoded_mesg);
 static herr_t H5SM_type_to_flag(unsigned type_id, unsigned *type_flag);
 static herr_t H5SM_read_iter_op(H5O_t *oh, H5O_mesg_t *mesg, unsigned sequence,
     unsigned *oh_modified, void *_udata);
@@ -1518,6 +1518,7 @@ H5SM_delete(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, H5O_shared_t *sh_mesg)
     unsigned              cache_flags = H5AC__NO_FLAGS_SET;
     H5SM_table_cache_ud_t cache_udata;      /* User-data for callback */
     ssize_t               index_num;
+    size_t                mesg_size = 0;
     void                 *mesg_buf = NULL;
     void                 *native_mesg = NULL;
     unsigned              type_id;              /* Message type ID to operate on */
@@ -1547,8 +1548,8 @@ H5SM_delete(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, H5O_shared_t *sh_mesg)
      * zero and any file space it uses needs to be freed.  mesg_buf holds the
      * serialized form of the message.
      */
-    if(H5SM_delete_from_index(f, dxpl_id, open_oh, &(table->indexes[index_num]), sh_mesg, &cache_flags, &mesg_buf) < 0)
-	HGOTO_ERROR(H5E_SOHM, H5E_CANTDELETE, FAIL, "unable to delete mesage from SOHM index")
+    if(H5SM_delete_from_index(f, dxpl_id, open_oh, &(table->indexes[index_num]), sh_mesg, &cache_flags, &mesg_size, &mesg_buf) < 0)
+        HGOTO_ERROR(H5E_SOHM, H5E_CANTDELETE, FAIL, "unable to delete mesage from SOHM index")
 
     /* Release the master SOHM table */
     if(H5AC_unprotect(f, dxpl_id, H5AC_SOHM_TABLE, H5F_SOHM_ADDR(f), table, cache_flags) < 0)
@@ -1560,7 +1561,7 @@ H5SM_delete(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh, H5O_shared_t *sh_mesg)
      * master table needs to be unprotected when we do this.
      */
     if(mesg_buf) {
-        if(NULL == (native_mesg = H5O_msg_decode(f, dxpl_id, open_oh, type_id, (const unsigned char *)mesg_buf)))
+        if(NULL == (native_mesg = H5O_msg_decode(f, dxpl_id, open_oh, type_id, mesg_size, (const unsigned char *)mesg_buf)))
             HGOTO_ERROR(H5E_SOHM, H5E_CANTDECODE, FAIL, "can't decode shared message.")
 
         if(H5O_msg_delete(f, dxpl_id, open_oh, type_id, native_mesg) < 0)
@@ -1747,7 +1748,7 @@ H5SM_decr_ref(void *record, void *op_data, hbool_t *changed)
 static herr_t
 H5SM_delete_from_index(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
     H5SM_index_header_t *header, const H5O_shared_t *mesg,
-    unsigned *cache_flags, void ** /*out*/ encoded_mesg)
+    unsigned *cache_flags, size_t * /*out*/ mesg_size, void ** /*out*/ encoded_mesg)
 {
     H5SM_list_t     *list = NULL;
     H5SM_mesg_key_t key;
@@ -1879,6 +1880,7 @@ H5SM_delete_from_index(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
 
         /* Return the message's encoding so anything it references can be freed */
         *encoded_mesg = encoding_buf;
+        *mesg_size = buf_size;
 
         /* If there are no messages left in the index, delete it */
         if(header->num_messages == 0) {
@@ -1920,8 +1922,10 @@ done:
     /* Free the message encoding, if we're not returning it in encoded_mesg
      * or if there's been an error.
      */
-    if(encoding_buf && (NULL == *encoded_mesg || ret_value < 0))
+    if(encoding_buf && (NULL == *encoded_mesg || ret_value < 0)) {
         encoding_buf = H5MM_xfree(encoding_buf);
+        *mesg_size = 0;
+    }
 
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5SM_delete_from_index() */
diff --git a/src/H5T.c b/src/H5T.c
index d705b99..f4c10a5 100644
--- a/src/H5T.c
+++ b/src/H5T.c
@@ -298,8 +298,6 @@ static herr_t H5T_unregister(H5T_pers_t pers, const char *name, H5T_t *src,
 static herr_t H5T_register(H5T_pers_t pers, const char *name, H5T_t *src,
             H5T_t *dst, H5T_conv_t func, hid_t dxpl_id, hbool_t api_call);
 static htri_t H5T_compiler_conv(H5T_t *src, H5T_t *dst);
-static herr_t H5T_encode(H5T_t *obj, unsigned char *buf, size_t *nalloc);
-static H5T_t *H5T_decode(const unsigned char *buf);
 static herr_t H5T_set_size(H5T_t *dt, size_t size);
 
 
@@ -2801,8 +2799,13 @@ H5Tdecode(const void *buf)
     if(buf == NULL)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "empty buffer")
 
-    /* Create datatype by decoding buffer */
-    if(NULL == (dt = H5T_decode((const unsigned char *)buf)))
+    /* Create datatype by decoding buffer
+     * There is no way to get the size of the buffer, so we pass in
+     * SIZE_MAX and assume the caller knows what they are doing.
+     * Really fixing this will require an H5Tdecode2() call that
+     * takes a size parameter.
+     */
+    if(NULL == (dt = H5T_decode(SIZE_MAX, (const unsigned char *)buf)))
         HGOTO_ERROR(H5E_DATATYPE, H5E_CANTDECODE, FAIL, "can't decode object")
 
     /* Register the type and return the ID */
@@ -2834,7 +2837,7 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
+herr_t
 H5T_encode(H5T_t *obj, unsigned char *buf, size_t *nalloc)
 {
     size_t      buf_size;               /* Encoded size of datatype */
@@ -2890,8 +2893,8 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-static H5T_t *
-H5T_decode(const unsigned char *buf)
+H5T_t *
+H5T_decode(size_t buf_size, const unsigned char *buf)
 {
     H5F_t *f = NULL;            /* Fake file structure*/
     H5T_t *ret_value = NULL;    /* Return value */
@@ -2911,7 +2914,7 @@ H5T_decode(const unsigned char *buf)
         HGOTO_ERROR(H5E_DATATYPE, H5E_VERSION, NULL, "unknown version of encoded datatype")
 
     /* Decode the serialized datatype message */
-    if(NULL == (ret_value = (H5T_t *)H5O_msg_decode(f, H5AC_ind_dxpl_id, NULL, H5O_DTYPE_ID, buf)))
+    if(NULL == (ret_value = (H5T_t *)H5O_msg_decode(f, H5AC_ind_dxpl_id, NULL, H5O_DTYPE_ID, buf_size, buf)))
         HGOTO_ERROR(H5E_DATATYPE, H5E_CANTDECODE, NULL, "can't decode object")
 
     /* Mark datatype as being in memory now */
@@ -5171,6 +5174,11 @@ H5T_set_loc(H5T_t *dt, H5F_t *f, H5T_loc_t loc)
 
                             /* Check if the field changed size */
                             if(old_size != memb_type->shared->size) {
+
+                                /* Fail if the old_size is zero */
+                                if (0 == old_size)
+                                    HGOTO_ERROR(H5E_DATATYPE, H5E_BADVALUE, FAIL, "old_size of zero would cause division by zero");
+
                                 /* Adjust the size of the member */
                                 dt->shared->u.compnd.memb[i].size = (dt->shared->u.compnd.memb[i].size*memb_type->shared->size)/old_size;
 
diff --git a/src/H5Tprivate.h b/src/H5Tprivate.h
index 81af056..f519141 100644
--- a/src/H5Tprivate.h
+++ b/src/H5Tprivate.h
@@ -112,6 +112,8 @@ H5_DLL H5T_class_t H5T_get_class(const H5T_t *dt, htri_t internal);
 H5_DLL htri_t H5T_detect_class(const H5T_t *dt, H5T_class_t cls, hbool_t from_api);
 H5_DLL size_t H5T_get_size(const H5T_t *dt);
 H5_DLL int    H5T_cmp(const H5T_t *dt1, const H5T_t *dt2, hbool_t superset);
+H5_DLL herr_t H5T_encode(H5T_t *obj, unsigned char *buf, size_t *nalloc);
+H5_DLL H5T_t *H5T_decode(size_t buf_size, const unsigned char *buf);
 H5_DLL herr_t H5T_debug(const H5T_t *dt, FILE * stream);
 H5_DLL struct H5O_loc_t *H5T_oloc(H5T_t *dt);
 H5_DLL H5G_name_t *H5T_nameof(H5T_t *dt);