net/x25: fix incorrect parameter validation in the x25_getsockopt() function

[ Upstream commit d6eb8de2015f0c24822e47356f839167ebde2945 ]

The 'len' variable can't be negative when assigned the result of
'min_t' because all 'min_t' parameters are cast to unsigned int,
and then the minimum one is chosen.

To fix the logic, check 'len' as read from 'optlen',
where the types of relevant variables are (signed) int.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Gavrilov Ilia <Ilia.Gavrilov@infotecs.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c
index 0fb5143bec7ac45374f6b2e1c6133072c8e8145c..f15a4493eb0bf1a9c3c679ed5fdc41eed9c3d31f 100644 (file)
--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -460,12 +460,12 @@ static int x25_getsockopt(struct socket *sock, int level, int optname,
        if (get_user(len, optlen))
                goto out;
 
-       len = min_t(unsigned int, len, sizeof(int));
-
        rc = -EINVAL;
        if (len < 0)
                goto out;
 
+       len = min_t(unsigned int, len, sizeof(int));
+
        rc = -EFAULT;
        if (put_user(len, optlen))
                goto out;