From: Matthew Fernandez <matthew.fernandez@gmail.com>
Date: Mon, 26 Jul 2021 04:52:08 +0000 (-0700)
Subject: gcalloc: fix: do not abort on calloc(0, x) or calloc(x, 0) returning NULL
X-Git-Tag: 2.49.0~33^2
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=ba32fe4974335a0357d3abcf741b1113332ffd5d;p=graphviz

gcalloc: fix: do not abort on calloc(0, x) or calloc(x, 0) returning NULL

Commit 43a37bedd934bde50a6441766b85dfc9648abda9 added a `calloc` wrapper but
mistakenly did not account for it being valid for `calloc` to return `NULL` when
the input arguments are 0. This is unlikely to have caused a problem with Glibc
whose allocator typically returns non-null pointers even for 0 allocations.
However assuming a 0 allocation may return a null pointer is more portable.
---

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5a78175c8..221497370 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -25,6 +25,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   directory #2101
 - the generated gdefs.h header is no longer installed
 - `ccomps` out-of-memory message no longer incorrectly refers to `gc`
+- do not abort when `calloc(0, x)` or `calloc(x, 0)` in `gcalloc` return `NULL`
 
 ## [2.48.0] - 2021-07-17
 
diff --git a/lib/common/memory.c b/lib/common/memory.c
index f32dc21e1..6071a769e 100644
--- a/lib/common/memory.c
+++ b/lib/common/memory.c
@@ -38,7 +38,7 @@ void *zrealloc(void *ptr, size_t size, size_t elt, size_t osize)
 void *gcalloc(size_t nmemb, size_t size)
 {
     char *rv = calloc(nmemb, size);
-    if (UNLIKELY(rv == NULL)) {
+    if (UNLIKELY(nmemb > 0 && size > 0 && rv == NULL)) {
 	fprintf(stderr, "out of memory\n");
 	exit(EXIT_FAILURE);
     }