From 2592b1e93b713440a2fab51b01df4ad31bb21f7d Mon Sep 17 00:00:00 2001
From: "jan.nijtmans" <nijtmans@users.sourceforge.net>
Date: Thu, 10 Sep 2020 10:28:46 +0000
Subject: Don't use sizeof() for structs containing a flexible array as last
 element. Lesson from
 [https://core.tcl-lang.org/tk/info/3bc0f44ef3|3bc0f44ef3]. Use TclOffset in
 stead.

---
 generic/tclCompCmds.c  | 20 ++++++++++----------
 generic/tclEncoding.c  |  2 +-
 generic/tclStringRep.h |  4 ++--
 3 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/generic/tclCompCmds.c b/generic/tclCompCmds.c
index 607521d..c8970ce 100644
--- a/generic/tclCompCmds.c
+++ b/generic/tclCompCmds.c
@@ -403,9 +403,9 @@ TclCompileArraySetCmd(
     keyVar = AnonymousLocal(envPtr);
     valVar = AnonymousLocal(envPtr);
 
-    infoPtr = ckalloc(sizeof(ForeachInfo));
+    infoPtr = ckalloc(TclOffset(ForeachInfo, varLists) + sizeof(ForeachVarList *));
     infoPtr->numLists = 1;
-    infoPtr->varLists[0] = ckalloc(sizeof(ForeachVarList) + sizeof(int));
+    infoPtr->varLists[0] = ckalloc(TclOffset(ForeachVarList, varIndexes) + 2 * sizeof(int));
     infoPtr->varLists[0]->numVars = 2;
     infoPtr->varLists[0]->varIndexes[0] = keyVar;
     infoPtr->varLists[0]->varIndexes[1] = valVar;
@@ -1776,7 +1776,7 @@ TclCompileDictUpdateCmd(
      * that are to be used.
      */
 
-    duiPtr = ckalloc(sizeof(DictUpdateInfo) + sizeof(int) * (numVars - 1));
+    duiPtr = ckalloc(TclOffset(DictUpdateInfo, varIndices) + sizeof(int) * numVars);
     duiPtr->length = numVars;
     keyTokenPtrs = TclStackAlloc(interp, sizeof(Tcl_Token *) * numVars);
     tokenPtr = TokenAfter(dictVarTokenPtr);
@@ -2258,7 +2258,7 @@ DupDictUpdateInfo(
     unsigned len;
 
     dui1Ptr = clientData;
-    len = sizeof(DictUpdateInfo) + sizeof(int) * (dui1Ptr->length - 1);
+    len = TclOffset(DictUpdateInfo, varIndices) + sizeof(int) * dui1Ptr->length;
     dui2Ptr = ckalloc(len);
     memcpy(dui2Ptr, dui1Ptr, len);
     return dui2Ptr;
@@ -2712,8 +2712,8 @@ CompileEachloopCmd(
      */
 
     numLists = (numWords - 2)/2;
-    infoPtr = ckalloc(sizeof(ForeachInfo)
-	    + (numLists - 1) * sizeof(ForeachVarList *));
+    infoPtr = ckalloc(TclOffset(ForeachInfo, varLists)
+	    + numLists * sizeof(ForeachVarList *));
     infoPtr->numLists = 0;	/* Count this up as we go */
 
     /*
@@ -2746,8 +2746,8 @@ CompileEachloopCmd(
 	    goto done;
 	}
 
-	varListPtr = ckalloc(sizeof(ForeachVarList)
-		+ (numVars - 1) * sizeof(int));
+	varListPtr = ckalloc(TclOffset(ForeachVarList, varIndexes)
+		+ numVars * sizeof(int));
 	varListPtr->numVars = numVars;
 	infoPtr->varLists[i/2] = varListPtr;
 	infoPtr->numLists++;
@@ -2882,7 +2882,7 @@ DupForeachInfo(
     ForeachVarList *srcListPtr, *dupListPtr;
     int numVars, i, j, numLists = srcPtr->numLists;
 
-    dupPtr = ckalloc(sizeof(ForeachInfo)
+    dupPtr = ckalloc(TclOffset(ForeachInfo, varLists)
 	    + numLists * sizeof(ForeachVarList *));
     dupPtr->numLists = numLists;
     dupPtr->firstValueTemp = srcPtr->firstValueTemp;
@@ -2891,7 +2891,7 @@ DupForeachInfo(
     for (i = 0;  i < numLists;  i++) {
 	srcListPtr = srcPtr->varLists[i];
 	numVars = srcListPtr->numVars;
-	dupListPtr = ckalloc(sizeof(ForeachVarList)
+	dupListPtr = ckalloc(TclOffset(ForeachVarList, varIndexes)
 		+ numVars * sizeof(int));
 	dupListPtr->numVars = numVars;
 	for (j = 0;  j < numVars;  j++) {
diff --git a/generic/tclEncoding.c b/generic/tclEncoding.c
index 5c7aab8..6377ad8 100644
--- a/generic/tclEncoding.c
+++ b/generic/tclEncoding.c
@@ -2039,7 +2039,7 @@ LoadEscapeEncoding(
 	Tcl_DStringFree(&lineString);
     }
 
-    size = sizeof(EscapeEncodingData) - sizeof(EscapeSubTable)
+    size = TclOffset(EscapeEncodingData, subTables)
 	    + Tcl_DStringLength(&escapeData);
     dataPtr = (EscapeEncodingData *)ckalloc(size);
     dataPtr->initLen = strlen(init);
diff --git a/generic/tclStringRep.h b/generic/tclStringRep.h
index 227e6bc..6d179ba 100644
--- a/generic/tclStringRep.h
+++ b/generic/tclStringRep.h
@@ -65,9 +65,9 @@ typedef struct String {
 } String;
 
 #define STRING_MAXCHARS \
-    (int)(((size_t)UINT_MAX - sizeof(String))/sizeof(Tcl_UniChar))
+    (int)(((size_t)UINT_MAX - 1 - TclOffset(String, unicode))/sizeof(Tcl_UniChar))
 #define STRING_SIZE(numChars) \
-    (sizeof(String) + ((numChars) * sizeof(Tcl_UniChar)))
+    (TclOffset(String, unicode) + ((numChars + 1) * sizeof(Tcl_UniChar)))
 #define stringCheckLimits(numChars) \
     do {								\
 	if ((numChars) < 0 || (numChars) > STRING_MAXCHARS) {		\
-- 
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