CVE-2026-23120

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

l2tp: avoid one data-race in l2tp_tunnel_del_work()

We should read sk->sk_socket only when dealing with kernel sockets.

syzbot reported the following data-race:

BUG: KCSAN: data-race in l2tp_tunnel_del_work / sk_common_release

write to 0xffff88811c182b20 of 8 bytes by task 5365 on cpu 0:

sk_set_socket include/net/sock.h:2092 [inline]

sock_orphan include/net/sock.h:2118 [inline]

sk_common_release+0xae/0x230 net/core/sock.c:4003

udp_lib_close+0x15/0x20 include/net/udp.h:325

inet_release+0xce/0xf0 net/ipv4/af_inet.c:437

__sock_release net/socket.c:662 [inline]

sock_close+0x6b/0x150 net/socket.c:1455

__fput+0x29b/0x650 fs/file_table.c:468

____fput+0x1c/0x30 fs/file_table.c:496

task_work_run+0x131/0x1a0 kernel/task_work.c:233

resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]

__exit_to_user_mode_loop kernel/entry/common.c:44 [inline]

exit_to_user_mode_loop+0x1fe/0x740 kernel/entry/common.c:75

__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]

syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]

syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]

syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]

do_syscall_64+0x1e1/0x2b0 arch/x86/entry/syscall_64.c:100

entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811c182b20 of 8 bytes by task 827 on cpu 1:

l2tp_tunnel_del_work+0x2f/0x1a0 net/l2tp/l2tp_core.c:1418

process_one_work kernel/workqueue.c:3257 [inline]

process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3340

worker_thread+0x582/0x770 kernel/workqueue.c:3421

kthread+0x489/0x510 kernel/kthread.c:463

ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158

ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

value changed: 0xffff88811b818000 -> 0x0000000000000000