CVE-2026-80848

In the Linux kernel, the following vulnerability has been resolved:

xfrm: espintcp: fix UAF during close

ZDI reported and analyzed a race condition during close for espintcp

sockets:

espintcp_close() frees emsg->skb via kfree_skb() without holding

any socket lock. Concurrently, the xfrm_trans_reinject work queue

invokes esp_output_tcp_finish() -> espintcp_push_skb() ->

espintcp_push_msgs() -> skb_send_sock_locked(), which reads the

same skb as a data source.

Fix this by adding a synchronize_rcu() call after resetting sk_prot,

since esp_output_tcp_finish() runs under RCU and won't use a socket

with sk_prot == &tcp_prot. Simply taking the socket lock in

espintcp_close() could lead to leaks, if esp_output_tcp_finish()

re-adds an skb in the slot we just freed. After this, the existing

barrier() is no longer needed.