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| author | Steffen Klassert <steffen.klassert@secunet.com> | 2018-11-22 07:26:24 +0100 |
|---|---|---|
| committer | Steffen Klassert <steffen.klassert@secunet.com> | 2018-11-22 10:09:39 +0100 |
| commit | 0152eee6fc3b84298bb6a79961961734e8afa5b8 (patch) | |
| tree | 0c97d1dc87bf2b54971bf0b215ddbd5a837a9fb5 | |
| parent | ca92e173ab34a4f7fc4128bd372bd96f1af6f507 (diff) | |
| download | linux-0152eee6fc3b84298bb6a79961961734e8afa5b8.tar.gz linux-0152eee6fc3b84298bb6a79961961734e8afa5b8.tar.bz2 linux-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>
| -rw-r--r-- | net/xfrm/xfrm_input.c | 7 |
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) |