============================================ WARNING: possible recursive locking detected 6.2.0-rc2-syzkaller-00316-ge9ffbf16caa6 #0 Not tainted -------------------------------------------- syz-executor.0/5515 is trying to acquire lock: ffff88806d13d338 (&br->multicast_lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] ffff88806d13d338 (&br->multicast_lock){+.-.}-{2:2}, at: br_ip4_multicast_query net/bridge/br_multicast.c:3268 [inline] ffff88806d13d338 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_ipv4_rcv net/bridge/br_multicast.c:3682 [inline] ffff88806d13d338 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_rcv+0x1598/0x6830 net/bridge/br_multicast.c:3798 but task is already holding lock: ffff88806d139338 (&br->multicast_lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] ffff88806d139338 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_port_query_expired+0x61/0x360 net/bridge/br_multicast.c:1752 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-executor.0/5515: #0: ffffc900200e7ca8 ((&pmctx->ip4_own_query.timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:31 [inline] #0: ffffc900200e7ca8 ((&pmctx->ip4_own_query.timer)){+.-.}-{0:0}, at: call_timer_fn+0xd4/0x7c0 kernel/time/timer.c:1690 #1: ffff88806d139338 (&br->multicast_lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] #1: ffff88806d139338 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_port_query_expired+0x61/0x360 net/bridge/br_multicast.c:1752 #2: ffffffff8c791a20 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x237/0x3ba0 net/core/dev.c:4166 #3: ffffffff8c791a20 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x237/0x3ba0 net/core/dev.c:4166 #4: ffffffff8c791a80 (rcu_read_lock){....}-{1:2}, at: br_dev_xmit+0x4/0x1620 net/bridge/br_device.c:29 stack backtrace: CPU: 2 PID: 5515 Comm: syz-executor.0 Not tainted 6.2.0-rc2-syzkaller-00316-ge9ffbf16caa6 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106 print_deadlock_bug kernel/locking/lockdep.c:2990 [inline] check_deadlock kernel/locking/lockdep.c:3033 [inline] validate_chain kernel/locking/lockdep.c:3818 [inline] __lock_acquire.cold+0x116/0x3a7 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 include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:350 [inline] br_ip4_multicast_query net/bridge/br_multicast.c:3268 [inline] br_multicast_ipv4_rcv net/bridge/br_multicast.c:3682 [inline] br_multicast_rcv+0x1598/0x6830 net/bridge/br_multicast.c:3798 br_dev_xmit+0x726/0x1620 net/bridge/br_device.c:89 __netdev_start_xmit include/linux/netdevice.h:4865 [inline] netdev_start_xmit include/linux/netdevice.h:4879 [inline] xmit_one net/core/dev.c:3583 [inline] dev_hard_start_xmit+0x1c2/0x990 net/core/dev.c:3599 __dev_queue_xmit+0x2cdf/0x3ba0 net/core/dev.c:4249 dev_queue_xmit include/linux/netdevice.h:3035 [inline] vlan_dev_hard_start_xmit+0x1bc/0x5c0 net/8021q/vlan_dev.c:124 __netdev_start_xmit include/linux/netdevice.h:4865 [inline] netdev_start_xmit include/linux/netdevice.h:4879 [inline] xmit_one net/core/dev.c:3583 [inline] dev_hard_start_xmit+0x1c2/0x990 net/core/dev.c:3599 __dev_queue_xmit+0x2cdf/0x3ba0 net/core/dev.c:4249 dev_queue_xmit include/linux/netdevice.h:3035 [inline] br_dev_queue_push_xmit+0x26e/0x740 net/bridge/br_forward.c:53 NF_HOOK include/linux/netfilter.h:302 [inline] __br_multicast_send_query+0x11c6/0x3b70 net/bridge/br_multicast.c:1656 br_multicast_send_query+0x266/0x4b0 net/bridge/br_multicast.c:1735 br_multicast_port_query_expired+0x2c3/0x360 net/bridge/br_multicast.c:1760 call_timer_fn+0x1da/0x7c0 kernel/time/timer.c:1700 expire_timers+0x2c6/0x5c0 kernel/time/timer.c:1751 __run_timers kernel/time/timer.c:2022 [inline] __run_timers kernel/time/timer.c:1995 [inline] run_timer_softirq+0x326/0x910 kernel/time/timer.c:2035 __do_softirq+0x1fb/0xadc kernel/softirq.c:571 invoke_softirq kernel/softirq.c:445 [inline] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:650 irq_exit_rcu+0x9/0x20 kernel/softirq.c:662 sysvec_apic_timer_interrupt+0x49/0xc0 arch/x86/kernel/apic/apic.c:1107 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:649 RIP: 0023:0xf7220159 Code: 5c 83 e8 08 89 da 39 cf 1b 54 24 04 73 24 89 74 24 04 8d b4 26 00 00 00 00 8b 48 f8 8b 50 fc 83 e8 08 89 de 39 cf 19 d6 72 ef <8b> 74 24 04 89 54 24 04 3b 44 24 08 76 39 8b 7c 24 04 8b 5c 24 0c RSP: 002b:00000000ffcd8b30 EFLAGS: 00000246 RAX: 00000000f6c67768 RBX: 00000000ffffffff RCX: 000000008890c650 RDX: 00000000ffffffff RSI: 0000000000000000 RDI: 0000000088912274 RBP: 00000000f6c67778 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ---------------- Code disassembly (best guess): 0: 5c pop %rsp 1: 83 e8 08 sub $0x8,%eax 4: 89 da mov %ebx,%edx 6: 39 cf cmp %ecx,%edi 8: 1b 54 24 04 sbb 0x4(%rsp),%edx c: 73 24 jae 0x32 e: 89 74 24 04 mov %esi,0x4(%rsp) 12: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi 19: 8b 48 f8 mov -0x8(%rax),%ecx 1c: 8b 50 fc mov -0x4(%rax),%edx 1f: 83 e8 08 sub $0x8,%eax 22: 89 de mov %ebx,%esi 24: 39 cf cmp %ecx,%edi 26: 19 d6 sbb %edx,%esi 28: 72 ef jb 0x19 * 2a: 8b 74 24 04 mov 0x4(%rsp),%esi <-- trapping instruction 2e: 89 54 24 04 mov %edx,0x4(%rsp) 32: 3b 44 24 08 cmp 0x8(%rsp),%eax 36: 76 39 jbe 0x71 38: 8b 7c 24 04 mov 0x4(%rsp),%edi 3c: 8b 5c 24 0c mov 0xc(%rsp),%ebx