From 23e9fcfef1f3d10675acce023592796851bcaf1a Mon Sep 17 00:00:00 2001 From: Alexey Kodanev Date: Tue, 12 Sep 2017 14:53:46 +0300 Subject: vti: fix NULL dereference in xfrm_input() Can be reproduced with LTP tests: # icmp-uni-vti.sh -p ah -a sha256 -m tunnel -S fffffffe -k 1 -s 10 IPv4: RIP: 0010:xfrm_input+0x7f9/0x870 ... Call Trace: vti_input+0xaa/0x110 [ip_vti] ? skb_free_head+0x21/0x40 vti_rcv+0x33/0x40 [ip_vti] xfrm4_ah_rcv+0x33/0x60 ip_local_deliver_finish+0x94/0x1e0 ip_local_deliver+0x6f/0xe0 ? ip_route_input_noref+0x28/0x50 ... # icmp-uni-vti.sh -6 -p ah -a sha256 -m tunnel -S fffffffe -k 1 -s 10 IPv6: RIP: 0010:xfrm_input+0x7f9/0x870 ... Call Trace: xfrm6_rcv_tnl+0x3c/0x40 vti6_rcv+0xd5/0xe0 [ip6_vti] xfrm6_ah_rcv+0x33/0x60 ip6_input_finish+0xee/0x460 ip6_input+0x3f/0xb0 ip6_rcv_finish+0x45/0xa0 ipv6_rcv+0x34b/0x540 xfrm_input() invokes xfrm_rcv_cb() -> vti_rcv_cb(), the last callback might call skb_scrub_packet(), which in turn can reset secpath. Fix it by adding a check that skb->sp is not NULL. Fixes: 7e9e9202bccc ("xfrm: Clear RX SKB secpath xfrm_offload") Signed-off-by: Alexey Kodanev Signed-off-by: Steffen Klassert --- net/xfrm/xfrm_input.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'net') diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c index 2515cd2bc5db..8ac9d32fb79d 100644 --- a/net/xfrm/xfrm_input.c +++ b/net/xfrm/xfrm_input.c @@ -429,7 +429,8 @@ resume: nf_reset(skb); if (decaps) { - skb->sp->olen = 0; + if (skb->sp) + skb->sp->olen = 0; skb_dst_drop(skb); gro_cells_receive(&gro_cells, skb); return 0; @@ -440,7 +441,8 @@ resume: err = x->inner_mode->afinfo->transport_finish(skb, xfrm_gro || async); if (xfrm_gro) { - skb->sp->olen = 0; + if (skb->sp) + skb->sp->olen = 0; skb_dst_drop(skb); gro_cells_receive(&gro_cells, skb); return err; -- cgit v1.2.3