[PATCH] DCCP: proper optlen checking in do_dccp_getsockopt()

[Jiri Kosina]

From: Jiri Kosina <jkosina@xxxxxxx>

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@xxxxxxxxxxx>
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>

 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);