PF_BRIDGE: br_mdb_parse() with unknown ifindex
PF_BRIDGE: br_mdb_parse() with unknown ifindex
INFO: rcu_sched self-detected stall on CPU
	1-....: (124999 ticks this GP) idle=c32/1/4611686018427387906 softirq=26433/26433 fqs=31215 
	 (t=125000 jiffies g=13693 c=13692 q=195)
NMI backtrace for cpu 1
CPU: 1 PID: 11515 Comm: syz-executor0 Not tainted 4.15.0-rc6-mm1+ #51
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x137/0x198 lib/dump_stack.c:53
 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103
 nmi_trigger_cpumask_backtrace+0x122/0x180 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:156 [inline]
 rcu_dump_cpu_stacks+0x186/0x1d7 kernel/rcu/tree.c:1375
 print_cpu_stall kernel/rcu/tree.c:1524 [inline]
 check_cpu_stall kernel/rcu/tree.c:1592 [inline]
 __rcu_pending kernel/rcu/tree.c:3362 [inline]
 rcu_pending kernel/rcu/tree.c:3424 [inline]
 rcu_check_callbacks+0x1a64/0x1de0 kernel/rcu/tree.c:2764
 update_process_times+0x30/0x60 kernel/time/timer.c:1628
 tick_sched_handle+0x85/0x160 kernel/time/tick-sched.c:162
 tick_sched_timer+0x42/0x120 kernel/time/tick-sched.c:1176
 __run_hrtimer kernel/time/hrtimer.c:1210 [inline]
 __hrtimer_run_queues+0x2c8/0xb50 kernel/time/hrtimer.c:1274
 hrtimer_interrupt+0x1c2/0x5e0 kernel/time/hrtimer.c:1308
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
 smp_apic_timer_interrupt+0xc9/0x4c0 arch/x86/kernel/apic/apic.c:1050
 apic_timer_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:920
 </IRQ>
RIP: 0010:mulaw_decode+0x516/0x740 sound/core/oss/mulaw.c:193
RSP: 0018:ffff8801cba67948 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff11
RAX: ffffc9000129d2ce RBX: ffffc900012a0167 RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffff8801cba67a02 RDI: ffffc9000129d2d0
RBP: ffff8801cba67a68 R08: fffff52000253a5a R09: fffff52000253a5a
R10: 0000000000000001 R11: fffff52000253a59 R12: 0000000000000002
R13: ffffc9000129d2ce R14: ffff8801d17ec900 R15: dffffc0000000000
 mulaw_transfer+0x222/0x270 sound/core/oss/mulaw.c:273
 snd_pcm_plug_write_transfer+0x22c/0x390 sound/core/oss/pcm_plugin.c:619
 snd_pcm_oss_write2+0x22e/0x3c0 sound/core/oss/pcm_oss.c:1310
 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1371 [inline]
 snd_pcm_oss_write+0x4c1/0x690 sound/core/oss/pcm_oss.c:2645
 __vfs_write+0xef/0x740 fs/read_write.c:480
 vfs_write+0x189/0x510 fs/read_write.c:544
 SYSC_write fs/read_write.c:589 [inline]
 SyS_write+0xd4/0x1a0 fs/read_write.c:581
 entry_SYSCALL_64_fastpath+0x23/0x9a
RIP: 0033:0x452ac9
RSP: 002b:00007f38d8b09c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f38d8b0a700 RCX: 0000000000452ac9
RDX: 00000000ffffffa2 RSI: 0000000020001000 RDI: 0000000000000013
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000000
R13: 0000000000a2f7ef R14: 00007f38d8b0a9c0 R15: 0000000000000000