On Thu, Jan 4, 2018 at 2:57 PM, syzbot syzbot+ebf0a29fce8f37153f57@syzkaller.appspotmail.com wrote:

Hello,

syzkaller hit the following crash on ad036b63ee57df9ab802a4eb20cbbbec66aa4520 git://git.cmpxchg.org/linux-mmots.git/master compiler: gcc (GCC) 7.1.1 20170620 .config is attached Raw console output is attached. Unfortunately, I don't have any reproducer for this bug yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+ebf0a29fce8f37153f57@syzkaller.appspotmail.com It will help syzbot understand when the bug is fixed. See footer for details. If you forward the report, please keep this part and the footer.

INFO: rcu_sched self-detected stall on CPU 1-....: (124999 ticks this GP) idle=71e/1/4611686018427387906 softirq=9229/9229 fqs=31218 (t=125000 jiffies g=4571 c=4570 q=876) NMI backtrace for cpu 1 CPU: 1 PID: 4500 Comm: syz-executor6 Not tainted 4.15.0-rc6-mm1+ #50 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:__memcpy+0x0/0x20 RSP: 0018:ffff8801cd597918 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff11 RAX: fffff52000255558 RBX: 0000000000000002 RCX: ffffffff83b7d25e RDX: 0000000000000002 RSI: ffff8801cd597a00 RDI: ffffc900012aaab8 RBP: ffff8801cd597938 R08: fffff52000255558 R09: fffff52000255558 R10: 0000000000000001 R11: fffff52000255557 R12: ffffc900012aaab8 R13: ffff8801cd597a00 R14: ffff8801d0e45000 R15: dffffc0000000000 memcpy include/linux/string.h:344 [inline] cvt_s16_to_native sound/core/oss/mulaw.c:164 [inline] mulaw_decode+0x50e/0x740 sound/core/oss/mulaw.c:195 mulaw_transfer+0x222/0x270 sound/core/oss/mulaw.c:273 snd_pcm_plug_write_transfer+0x20b/0x390 sound/core/oss/pcm_plugin.c:611 snd_pcm_oss_write2+0x22e/0x3c0 sound/core/oss/pcm_oss.c:1311 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1372 [inline] snd_pcm_oss_write+0x4c1/0x690 sound/core/oss/pcm_oss.c:2646 __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:00007febc940bc58 EFLAGS: 00000212 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 000000000071bf58 RCX: 0000000000452ac9 RDX: 00000000ffffffa2 RSI: 0000000020001000 RDI: 0000000000000013 RBP: 0000000000000521 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f5bb8 R13: 00000000ffffffff R14: 00007febc940c6d4 R15: 000000000000000b

+ALSA maintainers

This looks like:

#syz dup: INFO: rcu detected stall in memcpy

right?

---

This bug is generated by a dumb bot. It may contain errors. See https://goo.gl/tpsmEJ for details. Direct all questions to syzkaller@googlegroups.com.

syzbot will keep track of this bug report. If you forgot to add the Reported-by tag, once the fix for this bug is merged into any tree, please reply to this email with: #syz fix: exact-commit-title To mark this as a duplicate of another syzbot report, please reply with: #syz dup: exact-subject-of-another-report If it's a one-off invalid bug report, please reply with: #syz invalid Note: if the crash happens again, it will cause creation of a new bug report. Note: all commands must start from beginning of the line in the email body.

-- You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/94eb2c19de60c6629d0561f3b76.... For more options, visit https://groups.google.com/d/optout.