linux-kernel - [PATCH 2.6.32 27/62] x86_64: Fix strnlen_user() to not touch memory after specified maximum

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Message-Id: <20150912225607.725561395@1wt.eu>
Date:	Sun, 13 Sep 2015 00:56:33 +0200
From:	Willy Tarreau <w@....eu>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Ben Hutchings <ben@...adent.org.uk>, Jan Kara <jack@...e.cz>,
	Willy Tarreau <w@....eu>
Subject: [PATCH 2.6.32 27/62] x86_64: Fix strnlen_user() to not touch memory after
 specified maximum

2.6.32-longterm review patch.  If anyone has any objections, please let me know.

------------------

From: Ben Hutchings <ben@...adent.org.uk>

Inspired by commit f18c34e483ff ("lib: Fix strnlen_user() to not touch
memory after specified maximum") upstream.  This version of
strnlen_user(), no longer present upstream, has a similar off-by-one
error.

Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Cc: Jan Kara <jack@...e.cz>
(cherry picked from commit 4797489ce83a5f42d0b38089695a48d4a3d1ee0b)

Signed-off-by: Willy Tarreau <w@....eu>
---
 arch/x86/lib/usercopy_64.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c
index b7c2849..3428d91 100644
--- a/arch/x86/lib/usercopy_64.c
+++ b/arch/x86/lib/usercopy_64.c
@@ -113,7 +113,7 @@ long __strnlen_user(const char __user *s, long n)
 	char c;
 
 	while (1) {
-		if (res>n)
+		if (res >= n)
 			return n+1;
 		if (__get_user(c, s))
 			return 0;
-- 
1.7.12.2.21.g234cd45.dirty



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