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 f7a7c7798c3b2b1ad6977af2eefe541e991f2591..d18d51412cc003b6fd76928754375e0934876bfe 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;