From 8045c0df98d4f14c54e5cb875f1c9c0ce89fe4ff Mon Sep 17 00:00:00 2001 From: Dong Chenchen Date: Tue, 9 Jun 2026 17:21:17 +0800 Subject: xfrm: Fix dev use-after-free in xfrm async resumption xfrm async resumption hold skb->dev refcnt until after transport_finish. However, xfrm_rcv_cb may modify skb->dev to tunnel dev without taking device reference, such as vti_rcv_cb. The subsequent async resumption will decrement the tunnel device's reference count, which lead to uaf of tunnel dev and refcnt leak of orig dev as below: unregister_netdevice: waiting for vti1 to become free. Usage count = -2 Stash the original skb->dev to fix refcnt imbalance. The new skb->dev set by xfrm_rcv_cb can race with device teardown. Extend rcu protection over xfrm_rcv_cb and transport_finish to prevent races. Fixes: 1c428b038400 ("xfrm: hold dev ref until after transport_finish NF_HOOK") Reported-by: Xu Chunxiao Signed-off-by: Dong Chenchen Signed-off-by: Steffen Klassert --- net/ipv4/xfrm4_input.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'net/ipv4') diff --git a/net/ipv4/xfrm4_input.c b/net/ipv4/xfrm4_input.c index c2eac844bcdb..f6f2a8ef3f88 100644 --- a/net/ipv4/xfrm4_input.c +++ b/net/ipv4/xfrm4_input.c @@ -76,8 +76,6 @@ int xfrm4_transport_finish(struct sk_buff *skb, int async) NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, dev_net(dev), NULL, skb, dev, NULL, xfrm4_rcv_encap_finish); - if (async) - dev_put(dev); return 0; } -- cgit v1.2.3