Avoid out-of-bounds read access before the beginning of the

[mandoc.git] / compat_reallocarray.c

diff --git a/compat_reallocarray.c b/compat_reallocarray.c
index 5fabd0b2a58adbfd01e67dd0f6478eeb0d2c70db..66151904257d3b8cf8085629704b0d850ce1f5f5 100644 (file)
--- a/compat_reallocarray.c
+++ b/compat_reallocarray.c
@@ -1,12 +1,13 @@
 #include "config.h"
 
-#ifdef HAVE_REALLOCARRAY
+#if HAVE_REALLOCARRAY
 
 int dummy;
 
 #else
 
-/*     $OpenBSD: malloc.c,v 1.158 2014/04/23 15:07:27 tedu Exp $       */
+/*     $Id: compat_reallocarray.c,v 1.4 2014/12/11 09:05:01 schwarze Exp $     */
+/*     $OpenBSD: reallocarray.c,v 1.2 2014/12/08 03:45:00 bcook Exp $  */
 /*
  * Copyright (c) 2008 Otto Moerbeek <otto@drijf.net>
  *
@@ -22,12 +23,17 @@ int dummy;
  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
+
 #include <sys/types.h>
 #include <errno.h>
 #include <stdint.h>
 #include <stdlib.h>
 
-#define MUL_NO_OVERFLOW (1UL << (sizeof(size_t) * 4))
+/*
+ * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
+ * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
+ */
+#define MUL_NO_OVERFLOW        ((size_t)1 << (sizeof(size_t) * 4))
 
 void *
 reallocarray(void *optr, size_t nmemb, size_t size)