linux-kernel - [PATCH] DCCP: proper optlen checking in do_dccp

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Date:	Wed, 28 Mar 2007 20:49:32 +0200 (CEST)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Arnaldo Carvalho de Melo <acme@...driva.com>
Cc:	Robert Święcki <jagger@...ecki.net>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] DCCP: proper optlen checking in do_dccp_getsockopt()

From: Jiri Kosina <jkosina@...e.cz>

DCCP: proper optlen checking in do_dccp_getsockopt()

Robert Swiecki discovered [1] a signedness bug in checking of
optlen in do_dccp_getsockopt(). This bug can allow user to
read parts of the kernel memory.

[1] http://www.securityfocus.com/archive/1/463934/30/0/threaded

Cc: Robert Święcki <jagger@...ecki.net>
Signed-off-by: Jiri Kosina <jkosina@...e.cz>

 net/dccp/proto.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index cf28c53..5239f26 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -575,7 +575,7 @@ static int do_dccp_getsockopt(struct sock *sk, int level, int optname,
 	if (get_user(len, optlen))
 		return -EFAULT;
 
-	if (len < sizeof(int))
+	if (len < 1)
 		return -EINVAL;
 
 	dp = dccp_sk(sk);