============================================ WARNING: possible recursive locking detected 6.5.0-rc2-syzkaller-00549-g6bfef2ec0172 #0 Not tainted -------------------------------------------- syz-fuzzer/5053 is trying to acquire lock: ffff88807dc09330 ( &br->multicast_lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] &br->multicast_lock){+.-.}-{2:2}, at: br_ip6_multicast_query net/bridge/br_multicast.c:3518 [inline] &br->multicast_lock){+.-.}-{2:2}, at: br_multicast_ipv6_rcv net/bridge/br_multicast.c:3914 [inline] &br->multicast_lock){+.-.}-{2:2}, at: br_multicast_rcv+0x21b6/0x6750 net/bridge/br_multicast.c:3969 but task is already holding lock: ffff888044231330 (&br->multicast_lock){+.-.}-{2:2} , at: spin_lock include/linux/spinlock.h:351 [inline] , at: br_multicast_port_query_expired+0x61/0x350 net/bridge/br_multicast.c:1900 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 5 locks held by syz-fuzzer/5053: #0: ffffc9000425fc28 ((&pmctx->ip6_own_query.timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:31 [inline] #0: ffffc9000425fc28 ((&pmctx->ip6_own_query.timer)){+.-.}-{0:0}, at: call_timer_fn+0xd5/0x580 kernel/time/timer.c:1690 #1: ffff888044231330 (&br->multicast_lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #1: ffff888044231330 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_port_query_expired+0x61/0x350 net/bridge/br_multicast.c:1900 #2: ffffffff8c9a6560 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x237/0x3d60 net/core/dev.c:4249 #3: ffffffff8c9a6560 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x237/0x3d60 net/core/dev.c:4249 #4: ffffffff8c9a65c0 (rcu_read_lock){....}-{1:2}, at: arch_static_branch arch/x86/include/asm/jump_label.h:27 [inline] #4: ffffffff8c9a65c0 (rcu_read_lock){....}-{1:2}, at: br_tc_skb_miss_set net/bridge/br_private.h:766 [inline] #4: ffffffff8c9a65c0 (rcu_read_lock){....}-{1:2}, at: br_dev_xmit+0xf0/0x1970 net/bridge/br_device.c:42 stack backtrace: CPU: 1 PID: 5053 Comm: syz-fuzzer Not tainted 6.5.0-rc2-syzkaller-00549-g6bfef2ec0172 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106 check_deadlock kernel/locking/lockdep.c:3070 [inline] validate_chain kernel/locking/lockdep.c:3863 [inline] __lock_acquire+0x2971/0x5de0 kernel/locking/lockdep.c:5144 lock_acquire kernel/locking/lockdep.c:5761 [inline] lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5726 __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_ip6_multicast_query net/bridge/br_multicast.c:3518 [inline] br_multicast_ipv6_rcv net/bridge/br_multicast.c:3914 [inline] br_multicast_rcv+0x21b6/0x6750 net/bridge/br_multicast.c:3969 br_dev_xmit+0x786/0x1970 net/bridge/br_device.c:90 __netdev_start_xmit include/linux/netdevice.h:4908 [inline] netdev_start_xmit include/linux/netdevice.h:4922 [inline] xmit_one net/core/dev.c:3537 [inline] dev_hard_start_xmit+0x13d/0x6c0 net/core/dev.c:3553 __dev_queue_xmit+0x9be/0x3d60 net/core/dev.c:4330 dev_queue_xmit include/linux/netdevice.h:3086 [inline] vlan_dev_hard_start_xmit+0x3af/0x5c0 net/8021q/vlan_dev.c:125 __netdev_start_xmit include/linux/netdevice.h:4908 [inline] netdev_start_xmit include/linux/netdevice.h:4922 [inline] xmit_one net/core/dev.c:3537 [inline] dev_hard_start_xmit+0x13d/0x6c0 net/core/dev.c:3553 __dev_queue_xmit+0x9be/0x3d60 net/core/dev.c:4330 dev_queue_xmit include/linux/netdevice.h:3086 [inline] br_dev_queue_push_xmit+0x26e/0x7b0 net/bridge/br_forward.c:53 NF_HOOK include/linux/netfilter.h:303 [inline] __br_multicast_send_query+0x238b/0x4110 net/bridge/br_multicast.c:1804 br_multicast_send_query+0x2ce/0x540 net/bridge/br_multicast.c:1883 br_multicast_port_query_expired+0x288/0x350 net/bridge/br_multicast.c:1908 call_timer_fn+0x1a0/0x580 kernel/time/timer.c:1700 expire_timers kernel/time/timer.c:1751 [inline] __run_timers+0x764/0xb10 kernel/time/timer.c:2022 run_timer_softirq+0x58/0xd0 kernel/time/timer.c:2035 __do_softirq+0x218/0x965 kernel/softirq.c:553 invoke_softirq kernel/softirq.c:427 [inline] __irq_exit_rcu kernel/softirq.c:632 [inline] irq_exit_rcu+0xb7/0x120 kernel/softirq.c:644 sysvec_apic_timer_interrupt+0x47/0xc0 arch/x86/kernel/apic/apic.c:1109 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:645 RIP: 0033:0x403ace Code: 48 89 6c 24 38 48 8d 6c 24 38 e8 0d 00 00 00 48 8b 6c 24 38 48 83 c4 40 c3 cc cc cc 49 89 f2 48 89 fa 48 89 ce 48 89 df 0f 05 <48> 3d 01 f0 ff ff 76 15 48 f7 d8 48 89 c1 48 c7 c0 ff ff ff ff 48 RSP: 002b:000000c00022f778 EFLAGS: 00000246 RAX: 0000000000000001 RBX: 0000000000000004 RCX: 0000000000403ace RDX: 0000000000000080 RSI: 000000c00022f840 RDI: 0000000000000004 RBP: 000000c00022f7c0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000247 R11: 0000000000000246 R12: 000000c00022f850 R13: 0000000000000000 R14: 000000c000de1380 R15: 0000000000000001