From: Matthew Fernandez <matthew.fernandez@gmail.com>
Date: Sat, 27 Aug 2022 15:45:31 +0000 (-0700)
Subject: cgraph memresize: fix out-of-bounds write on allocation failure
X-Git-Tag: 6.0.1~19^2~3
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=a99bf5be584425a1ea5edad38df494c971e4c332;p=graphviz

cgraph memresize: fix out-of-bounds write on allocation failure

Callers of this function appear to anticipate the possibility of failure, e.g.
`agrealloc`. But the function itself was attempting to zero newly allocated
memory even if the allocation call failed.
---

diff --git a/lib/cgraph/mem.c b/lib/cgraph/mem.c
index fb30fa812..bdc131f48 100644
--- a/lib/cgraph/mem.c
+++ b/lib/cgraph/mem.c
@@ -34,7 +34,7 @@ static void *memresize(void *heap, void *ptr, size_t oldsize,
 
     (void)heap;
     rv = realloc(ptr, request);
-    if (request > oldsize)
+    if (rv != NULL && request > oldsize)
 	memset((char *) rv + oldsize, 0, request - oldsize);
     return rv;
 }