Add junk/zero filling unit tests, and fix discovered bugs.

Fix growing large reallocation to junk fill new space.

Fix huge deallocation to junk fill when munmap is disabled.

9 files changed, 420 insertions, 31 deletions

diff --git a/Makefile.in b/Makefile.in
index 470495c..89d8255 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -108,13 +108,14 @@ C_TESTLIB_SRCS := $(srcroot)test/src/math.c $(srcroot)test/src/mtx.c \
 	$(srcroot)test/src/thd.c
 C_UTIL_INTEGRATION_SRCS := $(srcroot)src/util.c
 TESTS_UNIT := $(srcroot)test/unit/bitmap.c $(srcroot)test/unit/ckh.c \
-	$(srcroot)test/unit/hash.c $(srcroot)test/unit/mallctl.c \
-	$(srcroot)test/unit/math.c $(srcroot)test/unit/mq.c \
-	$(srcroot)test/unit/mtx.c $(srcroot)test/unit/ql.c \
-	$(srcroot)test/unit/qr.c $(srcroot)test/unit/quarantine.c \
-	$(srcroot)test/unit/rb.c $(srcroot)test/unit/rtree.c \
-	$(srcroot)test/unit/SFMT.c $(srcroot)test/unit/stats.c \
-	$(srcroot)test/unit/tsd.c $(srcroot)test/unit/util.c
+	$(srcroot)test/unit/hash.c $(srcroot)test/unit/junk.c \
+	$(srcroot)test/unit/mallctl.c $(srcroot)test/unit/math.c \
+	$(srcroot)test/unit/mq.c $(srcroot)test/unit/mtx.c \
+	$(srcroot)test/unit/ql.c $(srcroot)test/unit/qr.c \
+	$(srcroot)test/unit/quarantine.c $(srcroot)test/unit/rb.c \
+	$(srcroot)test/unit/rtree.c $(srcroot)test/unit/SFMT.c \
+	$(srcroot)test/unit/stats.c $(srcroot)test/unit/tsd.c \
+	$(srcroot)test/unit/util.c $(srcroot)test/unit/zero.c
 TESTS_INTEGRATION := $(srcroot)test/integration/aligned_alloc.c \
 	$(srcroot)test/integration/allocated.c \
 	$(srcroot)test/integration/mallocx.c \
diff --git a/include/jemalloc/internal/arena.h b/include/jemalloc/internal/arena.h
index 4151751..f092155 100644
--- a/include/jemalloc/internal/arena.h
+++ b/include/jemalloc/internal/arena.h
@@ -408,9 +408,12 @@ void	arena_alloc_junk_small(void *ptr, arena_bin_info_t *bin_info,
 #ifdef JEMALLOC_JET
 typedef void (arena_redzone_corruption_t)(void *, size_t, bool, size_t,
     uint8_t);
-extern arena_redzone_corruption_t *arena_redzone_corruption_fptr;
-#endif
+extern arena_redzone_corruption_t *arena_redzone_corruption;
+typedef void (arena_dalloc_junk_small_t)(void *, arena_bin_info_t *);
+extern arena_dalloc_junk_small_t *arena_dalloc_junk_small;
+#else
 void	arena_dalloc_junk_small(void *ptr, arena_bin_info_t *bin_info);
+#endif
 void	arena_quarantine_junk_small(void *ptr, size_t usize);
 void	*arena_malloc_small(arena_t *arena, size_t size, bool zero);
 void	*arena_malloc_large(arena_t *arena, size_t size, bool zero);
@@ -422,9 +425,17 @@ void	arena_dalloc_bin(arena_t *arena, arena_chunk_t *chunk, void *ptr,
     size_t pageind, arena_chunk_map_t *mapelm);
 void	arena_dalloc_small(arena_t *arena, arena_chunk_t *chunk, void *ptr,
     size_t pageind);
+#ifdef JEMALLOC_JET
+typedef void (arena_dalloc_junk_large_t)(void *, size_t);
+extern arena_dalloc_junk_large_t *arena_dalloc_junk_large;
+#endif
 void	arena_dalloc_large_locked(arena_t *arena, arena_chunk_t *chunk,
     void *ptr);
 void	arena_dalloc_large(arena_t *arena, arena_chunk_t *chunk, void *ptr);
+#ifdef JEMALLOC_JET
+typedef void (arena_ralloc_junk_large_t)(void *, size_t, size_t);
+extern arena_ralloc_junk_large_t *arena_ralloc_junk_large;
+#endif
 void	*arena_ralloc_no_move(void *ptr, size_t oldsize, size_t size,
     size_t extra, bool zero);
 void	*arena_ralloc(arena_t *arena, void *ptr, size_t oldsize, size_t size,
diff --git a/include/jemalloc/internal/huge.h b/include/jemalloc/internal/huge.h
index d987d37..dac23c6 100644
--- a/include/jemalloc/internal/huge.h
+++ b/include/jemalloc/internal/huge.h
@@ -23,6 +23,10 @@ void	*huge_ralloc_no_move(void *ptr, size_t oldsize, size_t size,
     size_t extra);
 void	*huge_ralloc(void *ptr, size_t oldsize, size_t size, size_t extra,
     size_t alignment, bool zero, bool try_tcache_dalloc);
+#ifdef JEMALLOC_JET
+typedef void (huge_dalloc_junk_t)(void *, size_t);
+extern huge_dalloc_junk_t *huge_dalloc_junk;
+#endif
 void	huge_dalloc(void *ptr, bool unmap);
 size_t	huge_salloc(const void *ptr);
 prof_ctx_t	*huge_prof_ctx_get(const void *ptr);
diff --git a/include/jemalloc/internal/private_symbols.txt b/include/jemalloc/internal/private_symbols.txt
index 0ad600b..10ac549 100644
--- a/include/jemalloc/internal/private_symbols.txt
+++ b/include/jemalloc/internal/private_symbols.txt
@@ -8,6 +8,7 @@ arena_boot
 arena_dalloc
 arena_dalloc_bin
 arena_dalloc_bin_locked
+arena_dalloc_junk_large
 arena_dalloc_junk_small
 arena_dalloc_large
 arena_dalloc_large_locked
@@ -52,6 +53,7 @@ arena_ptr_small_binind_get
 arena_purge_all
 arena_quarantine_junk_small
 arena_ralloc
+arena_ralloc_junk_large
 arena_ralloc_no_move
 arena_redzone_corruption
 arena_run_regind
@@ -194,6 +196,7 @@ hash_x86_32
 huge_allocated
 huge_boot
 huge_dalloc
+huge_dalloc_junk
 huge_malloc
 huge_mtx
 huge_ndalloc
diff --git a/src/arena.c b/src/arena.c
index 71057aa..536be29 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -1446,10 +1446,10 @@ arena_redzone_corruption(void *ptr, size_t usize, bool after,
 	    after ? "after" : "before", ptr, usize, byte);
 }
 #ifdef JEMALLOC_JET
-arena_redzone_corruption_t *arena_redzone_corruption_fptr =
-    arena_redzone_corruption;
 #undef arena_redzone_corruption
-#define	arena_redzone_corruption arena_redzone_corruption_fptr
+#define	arena_redzone_corruption JEMALLOC_N(arena_redzone_corruption)
+arena_redzone_corruption_t *arena_redzone_corruption =
+    JEMALLOC_N(arena_redzone_corruption_impl);
 #endif
 
 static void
@@ -1482,6 +1482,10 @@ arena_redzones_validate(void *ptr, arena_bin_info_t *bin_info, bool reset)
 		abort();
 }
 
+#ifdef JEMALLOC_JET
+#undef arena_dalloc_junk_small
+#define	arena_dalloc_junk_small JEMALLOC_N(arena_dalloc_junk_small_impl)
+#endif
 void
 arena_dalloc_junk_small(void *ptr, arena_bin_info_t *bin_info)
 {
@@ -1491,6 +1495,12 @@ arena_dalloc_junk_small(void *ptr, arena_bin_info_t *bin_info)
 	memset((void *)((uintptr_t)ptr - redzone_size), 0x5a,
 	    bin_info->reg_interval);
 }
+#ifdef JEMALLOC_JET
+#undef arena_dalloc_junk_small
+#define	arena_dalloc_junk_small JEMALLOC_N(arena_dalloc_junk_small)
+arena_dalloc_junk_small_t *arena_dalloc_junk_small =
+    JEMALLOC_N(arena_dalloc_junk_small_impl);
+#endif
 
 void
 arena_quarantine_junk_small(void *ptr, size_t usize)
@@ -1841,21 +1851,38 @@ arena_dalloc_small(arena_t *arena, arena_chunk_t *chunk, void *ptr,
 	arena_dalloc_bin(arena, chunk, ptr, pageind, mapelm);
 }
 
+#ifdef JEMALLOC_JET
+#undef arena_dalloc_junk_large
+#define	arena_dalloc_junk_large JEMALLOC_N(arena_dalloc_junk_large_impl)
+#endif
+static void
+arena_dalloc_junk_large(void *ptr, size_t usize)
+{
+
+	if (config_fill && opt_junk)
+		memset(ptr, 0x5a, usize);
+}
+#ifdef JEMALLOC_JET
+#undef arena_dalloc_junk_large
+#define	arena_dalloc_junk_large JEMALLOC_N(arena_dalloc_junk_large)
+arena_dalloc_junk_large_t *arena_dalloc_junk_large =
+    JEMALLOC_N(arena_dalloc_junk_large_impl);
+#endif
+
 void
 arena_dalloc_large_locked(arena_t *arena, arena_chunk_t *chunk, void *ptr)
 {
 
 	if (config_fill || config_stats) {
 		size_t pageind = ((uintptr_t)ptr - (uintptr_t)chunk) >> LG_PAGE;
-		size_t size = arena_mapbits_large_size_get(chunk, pageind);
+		size_t usize = arena_mapbits_large_size_get(chunk, pageind);
 
-		if (config_fill && config_stats && opt_junk)
-			memset(ptr, 0x5a, size);
+		arena_dalloc_junk_large(ptr, usize);
 		if (config_stats) {
 			arena->stats.ndalloc_large++;
-			arena->stats.allocated_large -= size;
-			arena->stats.lstats[(size >> LG_PAGE) - 1].ndalloc++;
-			arena->stats.lstats[(size >> LG_PAGE) - 1].curruns--;
+			arena->stats.allocated_large -= usize;
+			arena->stats.lstats[(usize >> LG_PAGE) - 1].ndalloc++;
+			arena->stats.lstats[(usize >> LG_PAGE) - 1].curruns--;
 		}
 	}
 
@@ -1967,6 +1994,26 @@ arena_ralloc_large_grow(arena_t *arena, arena_chunk_t *chunk, void *ptr,
 	return (true);
 }
 
+#ifdef JEMALLOC_JET
+#undef arena_ralloc_junk_large
+#define	arena_ralloc_junk_large JEMALLOC_N(arena_ralloc_junk_large_impl)
+#endif
+static void
+arena_ralloc_junk_large(void *ptr, size_t old_usize, size_t usize)
+{
+
+	if (config_fill && opt_junk) {
+		memset((void *)((uintptr_t)ptr + usize), 0x5a,
+		    old_usize - usize);
+	}
+}
+#ifdef JEMALLOC_JET
+#undef arena_ralloc_junk_large
+#define	arena_ralloc_junk_large JEMALLOC_N(arena_ralloc_junk_large)
+arena_ralloc_junk_large_t *arena_ralloc_junk_large =
+    JEMALLOC_N(arena_ralloc_junk_large_impl);
+#endif
+
 /*
  * Try to resize a large allocation, in order to avoid copying.  This will
  * always fail if growing an object, and the following run is already in use.
@@ -1990,10 +2037,7 @@ arena_ralloc_large(void *ptr, size_t oldsize, size_t size, size_t extra,
 
 		if (psize < oldsize) {
 			/* Fill before shrinking in order avoid a race. */
-			if (config_fill && opt_junk) {
-				memset((void *)((uintptr_t)ptr + psize), 0x5a,
-				    oldsize - psize);
-			}
+			arena_ralloc_junk_large(ptr, oldsize, psize);
 			arena_ralloc_large_shrink(arena, chunk, ptr, oldsize,
 			    psize);
 			return (false);
@@ -2001,10 +2045,16 @@ arena_ralloc_large(void *ptr, size_t oldsize, size_t size, size_t extra,
 			bool ret = arena_ralloc_large_grow(arena, chunk, ptr,
 			    oldsize, PAGE_CEILING(size),
 			    psize - PAGE_CEILING(size), zero);
-			if (config_fill && ret == false && zero == false &&
-			    opt_zero) {
-				memset((void *)((uintptr_t)ptr + oldsize), 0,
-				    size - oldsize);
+			if (config_fill && ret == false && zero == false) {
+				if (opt_junk) {
+					memset((void *)((uintptr_t)ptr +
+					    oldsize), 0xa5, isalloc(ptr,
+					    config_prof) - oldsize);
+				} else if (opt_zero) {
+					memset((void *)((uintptr_t)ptr +
+					    oldsize), 0, isalloc(ptr,
+					    config_prof) - oldsize);
+				}
 			}
 			return (ret);
 		}
diff --git a/src/huge.c b/src/huge.c
index ea9a2ad..766c80c 100644
--- a/src/huge.c
+++ b/src/huge.c
@@ -182,6 +182,29 @@ huge_ralloc(void *ptr, size_t oldsize, size_t size, size_t extra,
 	return (ret);
 }
 
+#ifdef JEMALLOC_JET
+#undef huge_dalloc_junk
+#define	huge_dalloc_junk JEMALLOC_N(huge_dalloc_junk_impl)
+#endif
+static void
+huge_dalloc_junk(void *ptr, size_t usize)
+{
+
+	if (config_fill && config_dss && opt_junk) {
+		/*
+		 * Only bother junk filling if the chunk isn't about to be
+		 * unmapped.
+		 */
+		if (config_munmap == false || (config_dss && chunk_in_dss(ptr)))
+			memset(ptr, 0x5a, usize);
+	}
+}
+#ifdef JEMALLOC_JET
+#undef huge_dalloc_junk
+#define	huge_dalloc_junk JEMALLOC_N(huge_dalloc_junk)
+huge_dalloc_junk_t *huge_dalloc_junk = JEMALLOC_N(huge_dalloc_junk_impl);
+#endif
+
 void
 huge_dalloc(void *ptr, bool unmap)
 {
@@ -204,8 +227,8 @@ huge_dalloc(void *ptr, bool unmap)
 
 	malloc_mutex_unlock(&huge_mtx);
 
-	if (unmap && config_fill && config_dss && opt_junk)
-		memset(node->addr, 0x5a, node->size);
+	if (unmap)
+		huge_dalloc_junk(node->addr, node->size);
 
 	chunk_dealloc(node->addr, node->size, unmap);
 
diff --git a/test/unit/junk.c b/test/unit/junk.c
new file mode 100644
index 0000000..e27db2f
--- /dev/null
+++ b/test/unit/junk.c
@@ -0,0 +1,219 @@
+#include "test/jemalloc_test.h"
+
+#ifdef JEMALLOC_FILL
+const char *malloc_conf =
+    "abort:false,junk:true,zero:false,redzone:true,quarantine:0";
+#endif
+
+static arena_dalloc_junk_small_t *arena_dalloc_junk_small_orig;
+static arena_dalloc_junk_large_t *arena_dalloc_junk_large_orig;
+static huge_dalloc_junk_t *huge_dalloc_junk_orig;
+static void *most_recently_junked;
+
+static void
+arena_dalloc_junk_small_intercept(void *ptr, arena_bin_info_t *bin_info)
+{
+	size_t i;
+
+	arena_dalloc_junk_small_orig(ptr, bin_info);
+	for (i = 0; i < bin_info->reg_size; i++) {
+		assert_c_eq(((char *)ptr)[i], 0x5a,
+		    "Missing junk fill for byte %zu/%zu of deallocated region",
+		    i, bin_info->reg_size);
+	}
+	most_recently_junked = ptr;
+}
+
+static void
+arena_dalloc_junk_large_intercept(void *ptr, size_t usize)
+{
+	size_t i;
+
+	arena_dalloc_junk_large_orig(ptr, usize);
+	for (i = 0; i < usize; i++) {
+		assert_c_eq(((char *)ptr)[i], 0x5a,
+		    "Missing junk fill for byte %zu/%zu of deallocated region",
+		    i, usize);
+	}
+	most_recently_junked = ptr;
+}
+
+static void
+huge_dalloc_junk_intercept(void *ptr, size_t usize)
+{
+
+	huge_dalloc_junk_orig(ptr, usize);
+	/*
+	 * The conditions under which junk filling actually occurs are nuanced
+	 * enough that it doesn't make sense to duplicate the decision logic in
+	 * test code, so don't actually check that the region is junk-filled.
+	 */
+	most_recently_junked = ptr;
+}
+
+static void
+test_junk(size_t sz_min, size_t sz_max)
+{
+	char *s;
+	size_t sz_prev, sz, i;
+
+	arena_dalloc_junk_small_orig = arena_dalloc_junk_small;
+	arena_dalloc_junk_small = arena_dalloc_junk_small_intercept;
+	arena_dalloc_junk_large_orig = arena_dalloc_junk_large;
+	arena_dalloc_junk_large = arena_dalloc_junk_large_intercept;
+	huge_dalloc_junk_orig = huge_dalloc_junk;
+	huge_dalloc_junk = huge_dalloc_junk_intercept;
+
+	sz_prev = 0;
+	s = (char *)mallocx(sz_min, 0);
+	assert_ptr_not_null((void *)s, "Unexpected mallocx() failure");
+
+	for (sz = sallocx(s, 0); sz <= sz_max;
+	    sz_prev = sz, sz = sallocx(s, 0)) {
+		if (sz_prev > 0) {
+			assert_c_eq(s[0], 'a',
+			    "Previously allocated byte %zu/%zu is corrupted",
+			    0, sz_prev);
+			assert_c_eq(s[sz_prev-1], 'a',
+			    "Previously allocated byte %zu/%zu is corrupted",
+			    sz_prev-1, sz_prev);
+		}
+
+		for (i = sz_prev; i < sz; i++) {
+			assert_c_eq(s[i], 0xa5,
+			    "Newly allocated byte %zu/%zu isn't junk-filled",
+			    i, sz);
+			s[i] = 'a';
+		}
+
+		if (xallocx(s, sz+1, 0, 0) == sz) {
+			void *junked = (void *)s;
+
+			s = (char *)rallocx(s, sz+1, 0);
+			assert_ptr_not_null((void *)s,
+			    "Unexpected rallocx() failure");
+			assert_ptr_eq(most_recently_junked, junked,
+			    "Expected region of size %zu to be junk-filled",
+			    sz);
+		}
+	}
+
+	dallocx(s, 0);
+	assert_ptr_eq(most_recently_junked, (void *)s,
+	    "Expected region of size %zu to be junk-filled", sz);
+
+	arena_dalloc_junk_small = arena_dalloc_junk_small_orig;
+	arena_dalloc_junk_large = arena_dalloc_junk_large_orig;
+	huge_dalloc_junk = huge_dalloc_junk_orig;
+}
+
+TEST_BEGIN(test_junk_small)
+{
+
+	test_skip_if(!config_fill);
+	test_junk(1, SMALL_MAXCLASS-1);
+}
+TEST_END
+
+TEST_BEGIN(test_junk_large)
+{
+
+	test_skip_if(!config_fill);
+	test_junk(SMALL_MAXCLASS+1, arena_maxclass);
+}
+TEST_END
+
+TEST_BEGIN(test_junk_huge)
+{
+
+	test_skip_if(!config_fill);
+	test_junk(arena_maxclass+1, chunksize*2);
+}
+TEST_END
+
+arena_ralloc_junk_large_t *arena_ralloc_junk_large_orig;
+static void *most_recently_trimmed;
+
+static void
+arena_ralloc_junk_large_intercept(void *ptr, size_t old_usize, size_t usize)
+{
+
+	arena_ralloc_junk_large_orig(ptr, old_usize, usize);
+	assert_zu_eq(old_usize, arena_maxclass, "Unexpected old_usize");
+	assert_zu_eq(usize, arena_maxclass-PAGE, "Unexpected usize");
+	most_recently_trimmed = ptr;
+}
+
+TEST_BEGIN(test_junk_large_ralloc_shrink)
+{
+	void *p1, *p2;
+
+	p1 = mallocx(arena_maxclass, 0);
+	assert_ptr_not_null(p1, "Unexpected mallocx() failure");
+
+	arena_ralloc_junk_large_orig = arena_ralloc_junk_large;
+	arena_ralloc_junk_large = arena_ralloc_junk_large_intercept;
+
+	p2 = rallocx(p1, arena_maxclass-PAGE, 0);
+	assert_ptr_eq(p1, p2, "Unexpected move during shrink");
+
+	arena_ralloc_junk_large = arena_ralloc_junk_large_orig;
+
+	assert_ptr_eq(most_recently_trimmed, p1,
+	    "Expected trimmed portion of region to be junk-filled");
+}
+TEST_END
+
+static bool detected_redzone_corruption;
+
+static void
+arena_redzone_corruption_replacement(void *ptr, size_t usize, bool after,
+    size_t offset, uint8_t byte)
+{
+
+	detected_redzone_corruption = true;
+}
+
+TEST_BEGIN(test_junk_redzone)
+{
+	char *s;
+	arena_redzone_corruption_t *arena_redzone_corruption_orig;
+
+	test_skip_if(!config_fill);
+
+	arena_redzone_corruption_orig = arena_redzone_corruption;
+	arena_redzone_corruption = arena_redzone_corruption_replacement;
+
+	/* Test underflow. */
+	detected_redzone_corruption = false;
+	s = (char *)mallocx(1, 0);
+	assert_ptr_not_null((void *)s, "Unexpected mallocx() failure");
+	s[-1] = 0xbb;
+	dallocx(s, 0);
+	assert_true(detected_redzone_corruption,
+	    "Did not detect redzone corruption");
+
+	/* Test overflow. */
+	detected_redzone_corruption = false;
+	s = (char *)mallocx(1, 0);
+	assert_ptr_not_null((void *)s, "Unexpected mallocx() failure");
+	s[sallocx(s, 0)] = 0xbb;
+	dallocx(s, 0);
+	assert_true(detected_redzone_corruption,
+	    "Did not detect redzone corruption");
+
+	arena_redzone_corruption = arena_redzone_corruption_orig;
+}
+TEST_END
+
+int
+main(void)
+{
+
+	return (test(
+	    test_junk_small,
+	    test_junk_large,
+	    test_junk_huge,
+	    test_junk_large_ralloc_shrink,
+	    test_junk_redzone));
+}
diff --git a/test/unit/quarantine.c b/test/unit/quarantine.c
index d8a65e2..4534923 100644
--- a/test/unit/quarantine.c
+++ b/test/unit/quarantine.c
@@ -73,8 +73,8 @@ TEST_BEGIN(test_quarantine_redzone)
 
 	test_skip_if(!config_fill);
 
-	arena_redzone_corruption_orig = arena_redzone_corruption_fptr;
-	arena_redzone_corruption_fptr = arena_redzone_corruption_replacement;
+	arena_redzone_corruption_orig = arena_redzone_corruption;
+	arena_redzone_corruption = arena_redzone_corruption_replacement;
 
 	/* Test underflow. */
 	detected_redzone_corruption = false;
@@ -94,7 +94,7 @@ TEST_BEGIN(test_quarantine_redzone)
 	assert_true(detected_redzone_corruption,
 	    "Did not detect redzone corruption");
 
-	arena_redzone_corruption_fptr = arena_redzone_corruption_orig;
+	arena_redzone_corruption = arena_redzone_corruption_orig;
 }
 TEST_END
 
diff --git a/test/unit/zero.c b/test/unit/zero.c
new file mode 100644
index 0000000..2fdae2f
--- /dev/null
+++ b/test/unit/zero.c
@@ -0,0 +1,78 @@
+#include "test/jemalloc_test.h"
+
+#ifdef JEMALLOC_FILL
+const char *malloc_conf =
+    "abort:false,junk:false,zero:true,redzone:false,quarantine:0";
+#endif
+
+static void
+test_zero(size_t sz_min, size_t sz_max)
+{
+	char *s;
+	size_t sz_prev, sz, i;
+
+	sz_prev = 0;
+	s = (char *)mallocx(sz_min, 0);
+	assert_ptr_not_null((void *)s, "Unexpected mallocx() failure");
+
+	for (sz = sallocx(s, 0); sz <= sz_max;
+	    sz_prev = sz, sz = sallocx(s, 0)) {
+		if (sz_prev > 0) {
+			assert_c_eq(s[0], 'a',
+			    "Previously allocated byte %zu/%zu is corrupted",
+			    0, sz_prev);
+			assert_c_eq(s[sz_prev-1], 'a',
+			    "Previously allocated byte %zu/%zu is corrupted",
+			    sz_prev-1, sz_prev);
+		}
+
+		for (i = sz_prev; i < sz; i++) {
+			assert_c_eq(s[i], 0x0,
+			    "Newly allocated byte %zu/%zu isn't zero-filled",
+			    i, sz);
+			s[i] = 'a';
+		}
+
+		if (xallocx(s, sz+1, 0, 0) == sz) {
+			s = (char *)rallocx(s, sz+1, 0);
+			assert_ptr_not_null((void *)s,
+			    "Unexpected rallocx() failure");
+		}
+	}
+
+	dallocx(s, 0);
+}
+
+TEST_BEGIN(test_zero_small)
+{
+
+	test_skip_if(!config_fill);
+	test_zero(1, SMALL_MAXCLASS-1);
+}
+TEST_END
+
+TEST_BEGIN(test_zero_large)
+{
+
+	test_skip_if(!config_fill);
+	test_zero(SMALL_MAXCLASS+1, arena_maxclass);
+}
+TEST_END
+
+TEST_BEGIN(test_zero_huge)
+{
+
+	test_skip_if(!config_fill);
+	test_zero(arena_maxclass+1, chunksize*2);
+}
+TEST_END
+
+int
+main(void)
+{
+
+	return (test(
+	    test_zero_small,
+	    test_zero_large,
+	    test_zero_huge));
+}