============================================ WARNING: possible recursive locking detected 6.8.0-syzkaller-05204-g237bb5f7f7f5 #0 Not tainted -------------------------------------------- syz-executor.1/4035 is trying to acquire lock: ffff88806364d3e0 (&br->multicast_lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff88806364d3e0 (&br->multicast_lock){+.-.}-{2:2}, at: br_ip4_multicast_query net/bridge/br_multicast.c:3440 [inline] ffff88806364d3e0 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_ipv4_rcv net/bridge/br_multicast.c:3854 [inline] ffff88806364d3e0 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_rcv+0x2d06/0x8180 net/bridge/br_multicast.c:3970 but task is already holding lock: ffff88807c42d3e0 (&br->multicast_lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff88807c42d3e0 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_port_query_expired+0x64/0x3b0 net/bridge/br_multicast.c:1905 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&br->multicast_lock); lock(&br->multicast_lock); *** DEADLOCK *** May be due to missing lock nesting notation 6 locks held by syz-executor.1/4035: #0: ffffffff8f385a08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:79 [inline] #0: ffffffff8f385a08 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x842/0x10d0 net/core/rtnetlink.c:6592 #1: ffffc90000007ca0 ((&pmctx->ip4_own_query.timer)){+.-.}-{0:0}, at: call_timer_fn+0xc0/0x600 kernel/time/timer.c:1789 #2: ffff88807c42d3e0 (&br->multicast_lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #2: ffff88807c42d3e0 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_port_query_expired+0x64/0x3b0 net/bridge/br_multicast.c:1905 #3: ffffffff8e131980 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #3: ffffffff8e131980 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:802 [inline] #3: ffffffff8e131980 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2c4/0x3b10 net/core/dev.c:4260 #4: ffffffff8e131980 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #4: ffffffff8e131980 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:802 [inline] #4: ffffffff8e131980 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2c4/0x3b10 net/core/dev.c:4260 #5: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline] #5: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline] #5: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: br_dev_xmit+0x1b9/0x1a10 net/bridge/br_device.c:44 stack backtrace: CPU: 0 PID: 4035 Comm: syz-executor.1 Not tainted 6.8.0-syzkaller-05204-g237bb5f7f7f5 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106 check_deadlock kernel/locking/lockdep.c:3062 [inline] validate_chain+0x15c1/0x58e0 kernel/locking/lockdep.c:3856 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137 lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] br_ip4_multicast_query net/bridge/br_multicast.c:3440 [inline] br_multicast_ipv4_rcv net/bridge/br_multicast.c:3854 [inline] br_multicast_rcv+0x2d06/0x8180 net/bridge/br_multicast.c:3970 br_dev_xmit+0xb17/0x1a10 net/bridge/br_device.c:90 __netdev_start_xmit include/linux/netdevice.h:4903 [inline] netdev_start_xmit include/linux/netdevice.h:4917 [inline] xmit_one net/core/dev.c:3531 [inline] dev_hard_start_xmit+0x26a/0x790 net/core/dev.c:3547 __dev_queue_xmit+0x19f4/0x3b10 net/core/dev.c:4335 dev_queue_xmit include/linux/netdevice.h:3091 [inline] vlan_dev_hard_start_xmit+0x36c/0x5f0 net/8021q/vlan_dev.c:125 __netdev_start_xmit include/linux/netdevice.h:4903 [inline] netdev_start_xmit include/linux/netdevice.h:4917 [inline] xmit_one net/core/dev.c:3531 [inline] dev_hard_start_xmit+0x26a/0x790 net/core/dev.c:3547 __dev_queue_xmit+0x19f4/0x3b10 net/core/dev.c:4335 dev_queue_xmit include/linux/netdevice.h:3091 [inline] br_dev_queue_push_xmit+0x701/0x8d0 net/bridge/br_forward.c:53 NF_HOOK include/linux/netfilter.h:314 [inline] __br_multicast_send_query+0x2ecb/0x4750 net/bridge/br_multicast.c:1809 br_multicast_send_query+0x4ee/0x6b0 net/bridge/br_multicast.c:1888 br_multicast_port_query_expired+0x2d4/0x3b0 net/bridge/br_multicast.c:1913 call_timer_fn+0x17e/0x600 kernel/time/timer.c:1792 expire_timers kernel/time/timer.c:1843 [inline] __run_timers kernel/time/timer.c:2408 [inline] __run_timer_base+0x66a/0x8e0 kernel/time/timer.c:2419 run_timer_base kernel/time/timer.c:2428 [inline] run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2438 __do_softirq+0x2bc/0x943 kernel/softirq.c:554 do_softirq+0x11b/0x1e0 kernel/softirq.c:455 __local_bh_enable_ip+0x1bb/0x200 kernel/softirq.c:382 spin_unlock_bh include/linux/spinlock.h:396 [inline] br_multicast_set_querier+0x1f9/0x250 net/bridge/br_multicast.c:4668 br_changelink+0x922/0x1840 net/bridge/br_netlink.c:1428 __rtnl_newlink net/core/rtnetlink.c:3663 [inline] rtnl_newlink+0x1853/0x20a0 net/core/rtnetlink.c:3727 rtnetlink_rcv_msg+0x89b/0x10d0 net/core/rtnetlink.c:6595 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2559 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline] netlink_unicast+0x7ea/0x980 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x8e1/0xcb0 net/netlink/af_netlink.c:1905 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x221/0x270 net/socket.c:745 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2584 ___sys_sendmsg net/socket.c:2638 [inline] __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2667 do_syscall_64+0xfb/0x240 entry_SYSCALL_64_after_hwframe+0x6d/0x75 RIP: 0033:0x7f5a5167dda9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f5a523d30c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f5a517abf80 RCX: 00007f5a5167dda9 RDX: 0000000000000000 RSI: 00000000200000c0 RDI: 0000000000000005 RBP: 00007f5a516ca47a R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000000b R14: 00007f5a517abf80 R15: 00007ffe1e3c71d8