====================================================== WARNING: possible circular locking dependency detected 6.2.0-rc3-syzkaller-00197-g87b93b678e95 #0 Not tainted ------------------------------------------------------ syz-executor.1/10886 is trying to acquire lock: ffff888075290f30 (slock-AF_INET6){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:355 [inline] ffff888075290f30 (slock-AF_INET6){+.-.}-{2:2}, at: release_sock+0x1f/0x1b0 net/core/sock.c:3483 but task is already holding lock: ffff888075291238 (clock-AF_INET6){++..}-{2:2}, at: l2tp_tunnel_register+0x2be/0x11e0 net/l2tp/l2tp_core.c:1484 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (clock-AF_INET6){++..}-{2:2}: __raw_write_lock_bh include/linux/rwlock_api_smp.h:202 [inline] _raw_write_lock_bh+0x33/0x40 kernel/locking/spinlock.c:334 sock_orphan include/net/sock.h:2094 [inline] inet_child_forget+0x73/0x2d0 net/ipv4/inet_connection_sock.c:1258 inet_csk_listen_stop+0x235/0x1110 net/ipv4/inet_connection_sock.c:1399 __tcp_close+0xc09/0xf50 net/ipv4/tcp.c:2873 tcp_close+0x2d/0xc0 net/ipv4/tcp.c:3032 inet_release+0x132/0x270 net/ipv4/af_inet.c:428 inet6_release+0x50/0x70 net/ipv6/af_inet6.c:489 __sock_release+0xcd/0x280 net/socket.c:650 sock_close+0x1c/0x20 net/socket.c:1365 __fput+0x27c/0xa90 fs/file_table.c:320 task_work_run+0x16f/0x270 kernel/task_work.c:179 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0xaa8/0x2950 kernel/exit.c:867 do_group_exit+0xd4/0x2a0 kernel/exit.c:1012 get_signal+0x21c3/0x2450 kernel/signal.c:2859 arch_do_signal_or_restart+0x79/0x5c0 arch/x86/kernel/signal.c:306 exit_to_user_mode_loop kernel/entry/common.c:168 [inline] exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:203 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline] syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:296 do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #0 (slock-AF_INET6){+.-.}-{2:2}: check_prev_add kernel/locking/lockdep.c:3097 [inline] check_prevs_add kernel/locking/lockdep.c:3216 [inline] validate_chain kernel/locking/lockdep.c:3831 [inline] __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055 lock_acquire kernel/locking/lockdep.c:5668 [inline] lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x33/0x40 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:355 [inline] release_sock+0x1f/0x1b0 net/core/sock.c:3483 l2tp_tunnel_register+0x3db/0x11e0 net/l2tp/l2tp_core.c:1487 l2tp_nl_cmd_tunnel_create+0x3d6/0x8b0 net/l2tp/l2tp_netlink.c:245 genl_family_rcv_msg_doit.isra.0+0x1e6/0x2d0 net/netlink/genetlink.c:968 genl_family_rcv_msg net/netlink/genetlink.c:1048 [inline] genl_rcv_msg+0x4ff/0x7e0 net/netlink/genetlink.c:1065 netlink_rcv_skb+0x165/0x440 net/netlink/af_netlink.c:2564 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1076 netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline] netlink_unicast+0x547/0x7f0 net/netlink/af_netlink.c:1356 netlink_sendmsg+0x91b/0xe10 net/netlink/af_netlink.c:1932 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg+0xd3/0x120 net/socket.c:734 ____sys_sendmsg+0x712/0x8c0 net/socket.c:2476 ___sys_sendmsg+0x110/0x1b0 net/socket.c:2530 __sys_sendmsg+0xf7/0x1c0 net/socket.c:2559 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(clock-AF_INET6); lock(slock-AF_INET6); lock(clock-AF_INET6); lock(slock-AF_INET6); *** DEADLOCK *** 4 locks held by syz-executor.1/10886: #0: ffffffff8e159a10 (cb_lock){++++}-{3:3}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1075 #1: ffffffff8e159ac8 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline] #1: ffffffff8e159ac8 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0x51a/0x7e0 net/netlink/genetlink.c:1063 #2: ffff888075290fb0 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1725 [inline] #2: ffff888075290fb0 (sk_lock-AF_INET6){+.+.}-{0:0}, at: l2tp_tunnel_register+0x2aa/0x11e0 net/l2tp/l2tp_core.c:1483 #3: ffff888075291238 (clock-AF_INET6){++..}-{2:2}, at: l2tp_tunnel_register+0x2be/0x11e0 net/l2tp/l2tp_core.c:1484 stack backtrace: CPU: 0 PID: 10886 Comm: syz-executor.1 Not tainted 6.2.0-rc3-syzkaller-00197-g87b93b678e95 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2177 check_prev_add kernel/locking/lockdep.c:3097 [inline] check_prevs_add kernel/locking/lockdep.c:3216 [inline] validate_chain kernel/locking/lockdep.c:3831 [inline] __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055 lock_acquire kernel/locking/lockdep.c:5668 [inline] lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x33/0x40 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:355 [inline] release_sock+0x1f/0x1b0 net/core/sock.c:3483 l2tp_tunnel_register+0x3db/0x11e0 net/l2tp/l2tp_core.c:1487 l2tp_nl_cmd_tunnel_create+0x3d6/0x8b0 net/l2tp/l2tp_netlink.c:245 genl_family_rcv_msg_doit.isra.0+0x1e6/0x2d0 net/netlink/genetlink.c:968 genl_family_rcv_msg net/netlink/genetlink.c:1048 [inline] genl_rcv_msg+0x4ff/0x7e0 net/netlink/genetlink.c:1065 netlink_rcv_skb+0x165/0x440 net/netlink/af_netlink.c:2564 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1076 netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline] netlink_unicast+0x547/0x7f0 net/netlink/af_netlink.c:1356 netlink_sendmsg+0x91b/0xe10 net/netlink/af_netlink.c:1932 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg+0xd3/0x120 net/socket.c:734 ____sys_sendmsg+0x712/0x8c0 net/socket.c:2476 ___sys_sendmsg+0x110/0x1b0 net/socket.c:2530 __sys_sendmsg+0xf7/0x1c0 net/socket.c:2559 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f0d4548c0c9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f0d43ffe168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f0d455ac050 RCX: 00007f0d4548c0c9 RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000006 RBP: 00007f0d454e7ae9 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffefbc4fd7f R14: 00007f0d43ffe300 R15: 0000000000022000