ipmr: fix incorrect parameter validation in the ip_mroute_getsockopt() function

[ Upstream commit 5c3be3e0eb44b7f978bb6cbb20ad956adb93f736 ]

The 'olr' 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 'olr' 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/ipv4/ipmr.c b/net/ipv4/ipmr.c
index e49242706b5f541d2d77777836f059e2851a2ee4..66eade3fb629f13869eaf890d13dca3a1f4632bf 100644 (file)
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -1603,9 +1603,11 @@ int ip_mroute_getsockopt(struct sock *sk, int optname, sockptr_t optval,
 
        if (copy_from_sockptr(&olr, optlen, sizeof(int)))
                return -EFAULT;
-       olr = min_t(unsigned int, olr, sizeof(int));
        if (olr < 0)
                return -EINVAL;
+
+       olr = min_t(unsigned int, olr, sizeof(int));
+
        if (copy_to_sockptr(optlen, &olr, sizeof(int)))
                return -EFAULT;
        if (copy_to_sockptr(optval, &val, olr))