From: Joerg Sonnenberger <joerg@bec.de>
Date: Tue, 1 Aug 2017 15:17:45 +0000 (+0200)
Subject: Don't call wmemmove if size is zero.
X-Git-Tag: v3.3.3~49
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9d5e5f32208a42fc3e7986645a791524939aa9e4;p=thirdparty%2Flibarchive.git

Don't call wmemmove if size is zero.

The data pointers can be NULL in this case and ISO C says this is UB.
---

diff --git a/libarchive/archive_string.c b/libarchive/archive_string.c
index 5ae09b626..392cc1103 100644
--- a/libarchive/archive_string.c
+++ b/libarchive/archive_string.c
@@ -36,6 +36,7 @@ __FBSDID("$FreeBSD: head/lib/libarchive/archive_string.c 201095 2009-12-28 02:33
  * without incurring additional memory allocations.
  */
 
+#include <assert.h>
 #ifdef HAVE_ERRNO_H
 #include <errno.h>
 #endif
@@ -214,7 +215,9 @@ archive_wstring_append(struct archive_wstring *as, const wchar_t *p, size_t s)
 {
 	if (archive_wstring_ensure(as, as->length + s + 1) == NULL)
 		return (NULL);
-	wmemmove(as->s + as->length, p, s);
+	assert(p != NULL);
+	if (s)
+		wmemmove(as->s + as->length, p, s);
 	as->length += s;
 	as->s[as->length] = 0;
 	return (as);