linux-kernel - [PATCH 2/2] string: teach strnstr() to not search past NUL-terminator

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Date:	Sat, 16 Jan 2010 18:57:01 -0200
From:	André Goddard Rosa <andre.goddard@...il.com>
To:	linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org
Cc:	André Goddard Rosa <andre.goddard@...il.com>,
	Li Zefan <lizf@...fujitsu.com>,
	Alex Riesen <raa.lkml@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 2/2] string: teach strnstr() to not search past NUL-terminator

As noticed by Alex Riesen at:
http://marc.info/?l=linux-kernel&m=126364040821071&w=2

Signed-off-by: André Goddard Rosa <andre.goddard@...il.com>
cc: Li Zefan <lizf@...fujitsu.com>
cc: Alex Riesen <raa.lkml@...il.com>
cc: Andrew Morton <akpm@...ux-foundation.org>
---
 lib/string.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/lib/string.c b/lib/string.c
index 0f86245..94bad34 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -689,11 +689,13 @@ EXPORT_SYMBOL(strstr);
  */
 char *strnstr(const char *s1, const char *s2, size_t len)
 {
-	size_t l1 = len, l2;
+	size_t l1, l2;
 
 	l2 = strlen(s2);
 	if (!l2)
 		return (char *)s1;
+	l1 = strlen(s1);
+	l1 = (l1 <= len) ? l1 : len;
 	while (l1 >= l2) {
 		l1--;
 		if (!memcmp(s1, s2, l2))
-- 
1.6.6.201.g56119

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