xfrm: Fix NULL pointer dereference on policy lookup

[ Upstream commit b1e3a5607034aa0a481c6f69a6893049406665fb ]

When xfrm interfaces are used in combination with namespaces
and ESP offload, we get a dst_entry NULL pointer dereference.
This is because we don't have a dst_entry attached in the ESP
offloading case and we need to do a policy lookup before the
namespace transition.

Fix this by expicit checking of skb_dst(skb) before accessing it.

Fixes: f203b76d78 ("xfrm: Add virtual xfrm interfaces")
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Steffen Klassert 2021-03-23 09:26:44 +01:00 committed by Greg Kroah-Hartman
parent bac7e764e5
commit f819977ad4

View File

@ -1098,7 +1098,7 @@ static inline int __xfrm_policy_check2(struct sock *sk, int dir,
return __xfrm_policy_check(sk, ndir, skb, family);
return (!net->xfrm.policy_count[dir] && !secpath_exists(skb)) ||
(skb_dst(skb)->flags & DST_NOPOLICY) ||
(skb_dst(skb) && (skb_dst(skb)->flags & DST_NOPOLICY)) ||
__xfrm_policy_check(sk, ndir, skb, family);
}