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 cdc0a1781fd28a1d851c730a07cbc9be4db5bbfb..db184cb826b95bdcdc5910ceff1fc66d4494c8e6 100644 (file)
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -1574,9 +1574,11 @@ 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))