CVE-2026-80848

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CVE-2026-80848

Summary: xfrm: espintcp: fix UAF during close

Details: 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.

References: https://git.kernel.org/stable/c/24efebecf415ba264adba0f0491cec436463a14f, https://git.kernel.org/stable/c/29121c5e6591da527e8e36ddac7120dc527f574d, https://git.kernel.org/stable/c/4b31a875693c480c611519faca46216514e3e052, https://git.kernel.org/stable/c/4bc0dfa28dca6fc0084203732695968049c44072, https://git.kernel.org/stable/c/54b41ad14da9a981131ab6e4d3f79321a503ea5d, https://git.kernel.org/stable/c/deb232e884877bf10b4ce2580909eedec986c284, https://git.kernel.org/stable/c/eb3bbf29c723fe75c0eb92be14f0ec92971fe272, https://git.kernel.org/stable/c/ed5d9102190c45fc70121c036b0626b740040b75, https://git.kernel.org/stable/c/ff8dd7a932f34409a56e1b91a1219340f17457e9, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80848.json, https://nvd.nist.gov/vuln/detail/CVE-2026-80848, https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git