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authorSteffen Klassert <steffen.klassert@secunet.com>2018-09-11 10:31:15 +0200
committerSteffen Klassert <steffen.klassert@secunet.com>2018-09-11 11:28:25 +0200
commit9e1437937807b0122e8da1ca8765be2adca9aee6 (patch)
tree9da838ab391fbc47b379d00dab98aefe0888639e /net/xfrm
parent782710e333a526780d65918d669cb96646983ba2 (diff)
xfrm: Fix NULL pointer dereference when skb_dst_force clears the dst_entry.
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>
Diffstat (limited to 'net/xfrm')
-rw-r--r--net/xfrm/xfrm_output.c4
-rw-r--r--net/xfrm/xfrm_policy.c4
2 files changed, 8 insertions, 0 deletions
diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c
index 89b178a78dc7..36d15a38ce5e 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 7c5e8978aeaa..626e0f4d1749 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -2548,6 +2548,10 @@ 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)) {