diff options
| author | Steffen Klassert <steffen.klassert@secunet.com> | 2018-09-11 10:31:15 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-11-04 14:52:37 +0100 |
| commit | 73c6f86060703daf8b7aa72c51451a6339164915 (patch) | |
| tree | 52c9eaabf631b84175fea8187f0fc5aa1b80ed3d | |
| parent | 35507aabf0e5e50525de25603328f09a7a629da5 (diff) | |
xfrm: Fix NULL pointer dereference when skb_dst_force clears the dst_entry.
[ Upstream commit 9e1437937807b0122e8da1ca8765be2adca9aee6 ]
Since commit 222d7dbd258d ("net: prevent dst uses after free")
skb_dst_force() might clear the dst_entry attached to the skb.
The xfrm code don't expect this to happen, so we crash with
a NULL pointer dereference in this case. Fix it by checking
skb_dst(skb) for NULL after skb_dst_force() and drop the packet
in cast the dst_entry was cleared.
Fixes: 222d7dbd258d ("net: prevent dst uses after free")
Reported-by: Tobias Hommel <netdev-list@genoetigt.de>
Reported-by: Kristian Evensen <kristian.evensen@gmail.com>
Reported-by: Wolfgang Walter <linux@stwm.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | net/xfrm/xfrm_output.c | 4 | ||||
| -rw-r--r-- | net/xfrm/xfrm_policy.c | 4 |
2 files changed, 8 insertions, 0 deletions
diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c index 35610cc881a9..c47660fba498 100644 --- a/net/xfrm/xfrm_output.c +++ b/net/xfrm/xfrm_output.c @@ -101,6 +101,10 @@ static int xfrm_output_one(struct sk_buff *skb, int err) spin_unlock_bh(&x->lock); skb_dst_force(skb); + if (!skb_dst(skb)) { + XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR); + goto error_nolock; + } if (xfrm_offload(skb)) { x->type_offload->encap(x, skb); diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index 2fb7a78308e1..37c32e73aaef 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -2550,6 +2550,10 @@ int __xfrm_route_forward(struct sk_buff *skb, unsigned short family) } skb_dst_force(skb); + if (!skb_dst(skb)) { + XFRM_INC_STATS(net, LINUX_MIB_XFRMFWDHDRERROR); + return 0; + } dst = xfrm_lookup(net, skb_dst(skb), &fl, NULL, XFRM_LOOKUP_QUEUE); if (IS_ERR(dst)) { |