syzbot


possible deadlock in br_multicast_rcv

Status: auto-obsoleted due to no activity on 2023/11/03 02:43
Reported-by: syzbot+714180b17aa12e4b2f6d@syzkaller.appspotmail.com
First crash: 215d, last: 215d
Similar bugs (5)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 possible deadlock in br_multicast_rcv C 1 371d 401d 0/1 upstream: reported C repro on 2023/01/21 00:08
linux-4.19 possible deadlock in br_multicast_rcv C error 1 398d 398d 0/1 upstream: reported C repro on 2023/01/24 01:03
upstream possible deadlock in br_multicast_rcv (3) bridge C done error 9 174d 405d 0/26 upstream: reported C repro on 2023/01/16 16:40
upstream possible deadlock in br_multicast_rcv (2) bridge 11 770d 899d 0/26 auto-closed as invalid on 2022/05/17 09:29
upstream possible deadlock in br_multicast_rcv bridge 2 1006d 1008d 0/26 auto-closed as invalid on 2021/09/03 11:13

Sample crash report:
============================================
WARNING: possible recursive locking detected
6.1.41-syzkaller #0 Not tainted
--------------------------------------------
segctord/26746 is trying to acquire lock:
ffff88808c425338 (&br->multicast_lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline]
ffff88808c425338 (&br->multicast_lock){+.-.}-{2:2}, at: br_ip6_multicast_query net/bridge/br_multicast.c:3345 [inline]
ffff88808c425338 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_ipv6_rcv net/bridge/br_multicast.c:3741 [inline]
ffff88808c425338 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_rcv+0x1072/0x7590 net/bridge/br_multicast.c:3796

but task is already holding lock:
ffff888084eb9338 (&br->multicast_lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline]
ffff888084eb9338 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_port_query_expired+0x64/0x3b0 net/bridge/br_multicast.c:1746

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 segctord/26746:
 #0: ffffffff8ce058a0 (console_lock){+.+.}-{0:0}, at: vprintk_emit+0xb8/0x1f0 kernel/printk/printk.c:2267
 #1: ffffc90000007bc0 ((&pmctx->ip6_own_query.timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:41 [inline]
 #1: ffffc90000007bc0 ((&pmctx->ip6_own_query.timer)){+.-.}-{0:0}, at: call_timer_fn+0xbd/0x6b0 kernel/time/timer.c:1464
 #2: ffff888084eb9338 (&br->multicast_lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline]
 #2: ffff888084eb9338 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_port_query_expired+0x64/0x3b0 net/bridge/br_multicast.c:1746
 #3: ffffffff8cf29740 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:306
 #4: ffffffff8cf29740 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:306
 #5: ffffffff8cf296e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:305

stack backtrace:
CPU: 0 PID: 26746 Comm: segctord Not tainted 6.1.41-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 print_deadlock_bug kernel/locking/lockdep.c:2991 [inline]
 check_deadlock kernel/locking/lockdep.c:3034 [inline]
 validate_chain+0x4726/0x58e0 kernel/locking/lockdep.c:3819
 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056
 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:350 [inline]
 br_ip6_multicast_query net/bridge/br_multicast.c:3345 [inline]
 br_multicast_ipv6_rcv net/bridge/br_multicast.c:3741 [inline]
 br_multicast_rcv+0x1072/0x7590 net/bridge/br_multicast.c:3796
 br_dev_xmit+0xad5/0x1840 net/bridge/br_device.c:89
 __netdev_start_xmit include/linux/netdevice.h:4853 [inline]
 netdev_start_xmit include/linux/netdevice.h:4867 [inline]
 xmit_one net/core/dev.c:3595 [inline]
 dev_hard_start_xmit+0x261/0x8c0 net/core/dev.c:3611
 __dev_queue_xmit+0x1b97/0x3c90 net/core/dev.c:4261
 dev_queue_xmit include/linux/netdevice.h:3021 [inline]
 vlan_dev_hard_start_xmit+0x3da/0x6b0 net/8021q/vlan_dev.c:124
 __netdev_start_xmit include/linux/netdevice.h:4853 [inline]
 netdev_start_xmit include/linux/netdevice.h:4867 [inline]
 xmit_one net/core/dev.c:3595 [inline]
 dev_hard_start_xmit+0x261/0x8c0 net/core/dev.c:3611
 __dev_queue_xmit+0x1b97/0x3c90 net/core/dev.c:4261
 dev_queue_xmit include/linux/netdevice.h:3021 [inline]
 br_dev_queue_push_xmit+0x6e6/0x8a0 net/bridge/br_forward.c:53
 NF_HOOK include/linux/netfilter.h:302 [inline]
 __br_multicast_send_query+0x2e36/0x46a0 net/bridge/br_multicast.c:1650
 br_multicast_send_query+0x502/0x6d0 net/bridge/br_multicast.c:1729
 br_multicast_port_query_expired+0x2d4/0x3b0 net/bridge/br_multicast.c:1754
 call_timer_fn+0x19e/0x6b0 kernel/time/timer.c:1474
 expire_timers kernel/time/timer.c:1519 [inline]
 __run_timers+0x67c/0x890 kernel/time/timer.c:1790
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1803
 __do_softirq+0x2e9/0xa4c kernel/softirq.c:571
 invoke_softirq kernel/softirq.c:445 [inline]
 __irq_exit_rcu+0x155/0x240 kernel/softirq.c:650
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:662
 sysvec_apic_timer_interrupt+0x91/0xb0 arch/x86/kernel/apic/apic.c:1106
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:649
RIP: 0010:console_emit_next_record+0xb70/0xda0 kernel/printk/printk.c:2740
Code: 00 48 8b 5c 24 68 44 0f b6 74 24 1f 4d 85 e4 75 07 e8 c4 0b 1c 00 eb 06 e8 bd 0b 1c 00 fb 48 c7 84 24 a0 00 00 00 0e 36 e0 45 <41> c7 44 1d 00 00 00 00 00 49 c7 44 1d 0a 00 00 00 00 49 c7 44 1d
RSP: 0018:ffffc900155ef6c0 EFLAGS: 00000293
RAX: ffffffff816dcf33 RBX: 1ffff92002abdeec RCX: ffff8880752c5940
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900155ef970 R08: ffffffff816dcf09 R09: fffffbfff2052c45
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000200
R13: dffffc0000000000 R14: 0000000000000001 R15: ffffc900155ef9e0
 console_unlock+0x278/0x6e0 kernel/printk/printk.c:2860
 vprintk_emit+0xd1/0x1f0 kernel/printk/printk.c:2268
 _printk+0xd1/0x111 kernel/printk/printk.c:2289
 __nilfs_msg+0x2a9/0x330 fs/nilfs2/super.c:78
 nilfs_segctor_thread+0x27a/0x1130 fs/nilfs2/segment.c:2580
 kthread+0x26e/0x300 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
 </TASK>
----------------
Code disassembly (best guess):
   0:	00 48 8b             	add    %cl,-0x75(%rax)
   3:	5c                   	pop    %rsp
   4:	24 68                	and    $0x68,%al
   6:	44 0f b6 74 24 1f    	movzbl 0x1f(%rsp),%r14d
   c:	4d 85 e4             	test   %r12,%r12
   f:	75 07                	jne    0x18
  11:	e8 c4 0b 1c 00       	call   0x1c0bda
  16:	eb 06                	jmp    0x1e
  18:	e8 bd 0b 1c 00       	call   0x1c0bda
  1d:	fb                   	sti
  1e:	48 c7 84 24 a0 00 00 	movq   $0x45e0360e,0xa0(%rsp)
  25:	00 0e 36 e0 45
* 2a:	41 c7 44 1d 00 00 00 	movl   $0x0,0x0(%r13,%rbx,1) <-- trapping instruction
  31:	00 00
  33:	49 c7 44 1d 0a 00 00 	movq   $0x0,0xa(%r13,%rbx,1)
  3a:	00 00
  3c:	49                   	rex.WB
  3d:	c7                   	.byte 0xc7
  3e:	44                   	rex.R
  3f:	1d                   	.byte 0x1d

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/07/26 02:43 linux-6.1.y 5302e81aa209 6756545c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in br_multicast_rcv
* Struck through repros no longer work on HEAD.