xfrm: Fix NULL pointer dereference when skb_dst_force clears the dst_entry.

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Since commit 222d7dbd25 ("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: 222d7dbd25 ("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>

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This commit is contained in:

Steffen Klassert 2018-09-11 10:31:15 +02:00

parent 782710e333

commit 9e14379378

2 changed files with 8 additions and 0 deletions

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4

net/xfrm/xfrm_output.c

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4

net/xfrm/xfrm_policy.c

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