============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz.3.4417/24462 is trying to acquire lock: ffff888032d715e0 (&br->multicast_lock){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:342 [inline] ffff888032d715e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_ip4_multicast_query net/bridge/br_multicast.c:3498 [inline] ffff888032d715e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_multicast_ipv4_rcv net/bridge/br_multicast.c:3912 [inline] ffff888032d715e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_multicast_rcv+0x2a6d/0x7640 net/bridge/br_multicast.c:4028 but task is already holding lock: ffff888033e095e0 (&br->multicast_lock){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:342 [inline] ffff888033e095e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_multicast_port_query_expired net/bridge/br_multicast.c:1901 [inline] ffff888033e095e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_ip4_multicast_port_query_expired+0x68/0x380 net/bridge/br_multicast.c:1920 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 8 locks held by syz.3.4417/24462: #0: ffffffff8fdd1a80 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline] #0: ffffffff8fdd1a80 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline] #0: ffffffff8fdd1a80 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x883/0x1bb0 net/core/rtnetlink.c:4122 #1: ffffc90000007ce0 ((&pmctx->ip4_own_query.timer)){+.-.}-{0:0}, at: call_timer_fn+0xd4/0x5e0 kernel/time/timer.c:1745 #2: ffff888033e095e0 (&br->multicast_lock){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:342 [inline] #2: ffff888033e095e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_multicast_port_query_expired net/bridge/br_multicast.c:1901 [inline] #2: ffff888033e095e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_ip4_multicast_port_query_expired+0x68/0x380 net/bridge/br_multicast.c:1920 #3: ffffffff8e95ce00 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #3: ffffffff8e95ce00 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:891 [inline] #3: ffffffff8e95ce00 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x2b6/0x3950 net/core/dev.c:4792 #4: ffffffff8e95ce00 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #4: ffffffff8e95ce00 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:891 [inline] #4: ffffffff8e95ce00 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x2b6/0x3950 net/core/dev.c:4792 #5: ffffffff8e95cda0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #5: ffffffff8e95cda0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #5: ffffffff8e95cda0 (rcu_read_lock){....}-{1:3}, at: bond_start_xmit+0xb4/0x1900 drivers/net/bonding/bond_main.c:5591 #6: ffffffff8e95ce00 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #6: ffffffff8e95ce00 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:891 [inline] #6: ffffffff8e95ce00 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x2b6/0x3950 net/core/dev.c:4792 #7: ffffffff8e95cda0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #7: ffffffff8e95cda0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #7: ffffffff8e95cda0 (rcu_read_lock){....}-{1:3}, at: br_dev_xmit+0x193/0x1990 net/bridge/br_device.c:52 stack backtrace: CPU: 0 UID: 0 PID: 24462 Comm: syz.3.4417 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3041 check_deadlock kernel/locking/lockdep.c:3093 [inline] validate_chain kernel/locking/lockdep.c:3895 [inline] __lock_acquire+0x253f/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 __raw_spin_lock include/linux/spinlock_api_smp.h:158 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:158 spin_lock include/linux/spinlock.h:342 [inline] br_ip4_multicast_query net/bridge/br_multicast.c:3498 [inline] br_multicast_ipv4_rcv net/bridge/br_multicast.c:3912 [inline] br_multicast_rcv+0x2a6d/0x7640 net/bridge/br_multicast.c:4028 br_dev_xmit+0xb67/0x1990 net/bridge/br_device.c:98 __netdev_start_xmit include/linux/netdevice.h:5379 [inline] netdev_start_xmit include/linux/netdevice.h:5388 [inline] xmit_one net/core/dev.c:3888 [inline] dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904 __dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4871 __bond_start_xmit drivers/net/bonding/bond_main.c:-1 [inline] bond_start_xmit+0xd5c/0x1900 drivers/net/bonding/bond_main.c:5593 __netdev_start_xmit include/linux/netdevice.h:5379 [inline] netdev_start_xmit include/linux/netdevice.h:5388 [inline] xmit_one net/core/dev.c:3888 [inline] dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904 __dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4871 dev_queue_xmit_accel include/linux/netdevice.h:3435 [inline] macvlan_queue_xmit drivers/net/macvlan.c:571 [inline] macvlan_start_xmit+0x3ba/0x600 drivers/net/macvlan.c:595 __netdev_start_xmit include/linux/netdevice.h:5379 [inline] netdev_start_xmit include/linux/netdevice.h:5388 [inline] xmit_one net/core/dev.c:3888 [inline] dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904 __dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4871 dev_queue_xmit include/linux/netdevice.h:3429 [inline] br_dev_queue_push_xmit+0x370/0x4b0 net/bridge/br_forward.c:53 NF_HOOK include/linux/netfilter.h:318 [inline] __br_multicast_send_query+0x3100/0x4840 net/bridge/br_multicast.c:1805 br_multicast_send_query+0x509/0x6b0 net/bridge/br_multicast.c:1884 br_multicast_port_query_expired net/bridge/br_multicast.c:1909 [inline] br_ip4_multicast_port_query_expired+0x2ab/0x380 net/bridge/br_multicast.c:1920 call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748 expire_timers kernel/time/timer.c:1799 [inline] __run_timers kernel/time/timer.c:2374 [inline] __run_timer_base+0x652/0x8b0 kernel/time/timer.c:2386 run_timer_base kernel/time/timer.c:2395 [inline] run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405 handle_softirqs+0x22a/0x840 kernel/softirq.c:622 do_softirq+0x76/0xd0 kernel/softirq.c:523 __local_bh_enable_ip+0xf8/0x130 kernel/softirq.c:450 spin_unlock_bh include/linux/spinlock.h:396 [inline] __ip6_ins_rt net/ipv6/route.c:1353 [inline] ip6_route_add+0xe8/0x1b0 net/ipv6/route.c:3965 addrconf_add_mroute+0x2d1/0x370 net/ipv6/addrconf.c:2559 addrconf_add_dev net/ipv6/addrconf.c:2577 [inline] addrconf_dev_config net/ipv6/addrconf.c:3491 [inline] addrconf_init_auto_addrs+0x4d7/0xa50 net/ipv6/addrconf.c:3579 addrconf_notify+0xb1e/0x1050 net/ipv6/addrconf.c:3759 notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85 call_netdevice_notifiers_extack net/core/dev.c:2287 [inline] call_netdevice_notifiers net/core/dev.c:2301 [inline] __dev_notify_flags+0x1a9/0x310 net/core/dev.c:9798 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9827 do_setlink+0xfa5/0x45a0 net/core/rtnetlink.c:3194 rtnl_group_changelink net/core/rtnetlink.c:3827 [inline] __rtnl_newlink net/core/rtnetlink.c:3995 [inline] rtnl_newlink+0x14ca/0x1bb0 net/core/rtnetlink.c:4123 rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:7009 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2551 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1895 sock_sendmsg_nosec net/socket.c:787 [inline] __sock_sendmsg net/socket.c:802 [inline] ____sys_sendmsg+0x972/0x9f0 net/socket.c:2698 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2752 __sys_sendmsg net/socket.c:2784 [inline] __do_sys_sendmsg net/socket.c:2789 [inline] __se_sys_sendmsg net/socket.c:2787 [inline] __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2787 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb24c39ce59 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fb24a5ee028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fb24c615fa0 RCX: 00007fb24c39ce59 RDX: 0000000000000000 RSI: 0000200000000180 RDI: 0000000000000008 RBP: 00007fb24c432d6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fb24c616038 R14: 00007fb24c615fa0 R15: 00007ffddf6a7108 ip6_tunnel: ip6tnl1 xmit: Local address not yet configured!