| Message ID | 20181001085855.12057-6-steffen.klassert@secunet.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | pull request (net): ipsec 2018-10-01 | expand |
On 10/01/2018 11:58 AM, Steffen Klassert wrote: > 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 Doesn't. > 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. In case? > 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> [...] MBR, Sergei
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)) {
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> --- net/xfrm/xfrm_output.c | 4 ++++ net/xfrm/xfrm_policy.c | 4 ++++ 2 files changed, 8 insertions(+)