From: Mike Frysinger <vapier@gentoo.org>
Date: Thu, 8 Oct 2009 00:41:56 +0000 (-0400)
Subject: Avoid malloc(0) in getdents parsers
X-Git-Tag: v4.5.19~15
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=229738ce4e5432023024d15b74541222228eb7b3;p=strace

Avoid malloc(0) in getdents parsers

On end of directory, getdents returns 0.  This return value is used to
then try and do malloc(0), but on some systems this will always return
NULL.  Since the code won't read the pointer in question if len is 0,
then don't bother calling malloc(0) and set the pointer to NULL ourself.
* file.c (sys_getdents, sys_getdents64): Avoid malloc(0) call.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
---

diff --git a/file.c b/file.c
index c6e3b52b..4a2512f4 100644
--- a/file.c
+++ b/file.c
@@ -2337,7 +2337,8 @@ sys_getdents(struct tcb *tcp)
 		return 0;
 	}
 	len = tcp->u_rval;
-	if ((buf = malloc(len)) == NULL) {
+	buf = len ? malloc(len) : NULL;
+	if (len && !buf) {
 		tprintf("%#lx, %lu", tcp->u_arg[1], tcp->u_arg[2]);
 		fprintf(stderr, "out of memory\n");
 		return 0;
@@ -2420,7 +2421,8 @@ sys_getdents64(struct tcb *tcp)
 		return 0;
 	}
 	len = tcp->u_rval;
-	if ((buf = malloc(len)) == NULL) {
+	buf = len ? malloc(len) : NULL;
+	if (len && !buf) {
 		tprintf("%#lx, %lu", tcp->u_arg[1], tcp->u_arg[2]);
 		fprintf(stderr, "out of memory\n");
 		return 0;