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authorSteffen Klassert <steffen.klassert@secunet.com>2018-11-22 07:26:24 +0100
committerSteffen Klassert <steffen.klassert@secunet.com>2018-11-22 10:09:39 +0100
commit0152eee6fc3b84298bb6a79961961734e8afa5b8 (patch)
tree0c97d1dc87bf2b54971bf0b215ddbd5a837a9fb5 /net/xfrm/xfrm_input.c
parentxfrm: Fix bucket count reported to userspace (diff)
downloadlinux-dev-0152eee6fc3b84298bb6a79961961734e8afa5b8.tar.xz
linux-dev-0152eee6fc3b84298bb6a79961961734e8afa5b8.zip
xfrm: Fix NULL pointer dereference in xfrm_input 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 doesn'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 case the dst_entry was cleared. We also move the skb_dst_force() to a codepath that is not used when the transformation was offloaded, because in this case we don't have a dst_entry attached to the skb. The output and forwarding path was already fixed by commit 9e1437937807 ("xfrm: Fix NULL pointer dereference when skb_dst_force clears the dst_entry.") Fixes: 222d7dbd258d ("net: prevent dst uses after free") Reported-by: Jean-Philippe Menil <jpmenil@gmail.com> Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Diffstat (limited to 'net/xfrm/xfrm_input.c')
-rw-r--r--net/xfrm/xfrm_input.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index 684c0bc01e2c..d5635908587f 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -346,6 +346,12 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
skb->sp->xvec[skb->sp->len++] = x;
+ skb_dst_force(skb);
+ if (!skb_dst(skb)) {
+ XFRM_INC_STATS(net, LINUX_MIB_XFRMINERROR);
+ goto drop;
+ }
+
lock:
spin_lock(&x->lock);
@@ -385,7 +391,6 @@ lock:
XFRM_SKB_CB(skb)->seq.input.low = seq;
XFRM_SKB_CB(skb)->seq.input.hi = seq_hi;
- skb_dst_force(skb);
dev_hold(skb->dev);
if (crypto_done)