From: Zhiling Zou ESP-in-TCP receives records through the TCP strparser. handle_esp() restores skb->dev from the saved skb_iif before passing the packet into the XFRM input path. Queued TCP data can be processed after the original ingress device has been removed, for example during veth or net namespace teardown. In that case dev_get_by_index_rcu() returns NULL. The XFRM IPv4 and IPv6 input paths both expect skb->dev to be valid while building the route lookup, so queued ESP-in-TCP data can dereference a NULL device. Drop the packet if the saved ingress device can no longer be resolved. Such a packet can no longer be routed through the normal XFRM receive path, and this preserves the existing behaviour for packets whose ingress device still exists. Fixes: e27cca96cd68 ("xfrm: add espintcp (RFC 8229)") Cc: stable@vger.kernel.org Reported-by: Vega Signed-off-by: Zhiling Zou Assisted-by: Codex:gpt-5.4 Reviewed-by: Ren Wei --- net/xfrm/espintcp.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/xfrm/espintcp.c b/net/xfrm/espintcp.c index 374e1b964438..fc01ce89492a 100644 --- a/net/xfrm/espintcp.c +++ b/net/xfrm/espintcp.c @@ -37,6 +37,11 @@ static void handle_esp(struct sk_buff *skb, struct sock *sk) rcu_read_lock(); skb->dev = dev_get_by_index_rcu(sock_net(sk), skb->skb_iif); + if (!skb->dev) { + XFRM_INC_STATS(sock_net(sk), LINUX_MIB_XFRMINERROR); + kfree_skb(skb); + goto out; + } local_bh_disable(); #if IS_ENABLED(CONFIG_IPV6) if (sk->sk_family == AF_INET6) @@ -45,6 +50,7 @@ static void handle_esp(struct sk_buff *skb, struct sock *sk) #endif xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, TCP_ENCAP_ESPINTCP); local_bh_enable(); +out: rcu_read_unlock(); } -- 2.43.0