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 161dc194e634221bce420f962d5cb04ce1ace8c8..a7ecf2956cdd6c3fc81a642f2ee906c16f67cf71 100644 (file)
--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -470,12 +470,12 @@ 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;