On Thu, Jan 4, 2018 at 1:57 PM, Takashi Iwai <tiwai@xxxxxxx> wrote: > On Thu, 04 Jan 2018 13:08:45 +0100, > Dmitry Vyukov wrote: >> >> On Thu, Jan 4, 2018 at 1:03 PM, syzbot >> <syzbot+387f48da65cb522abfe8@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: >> > Hello, >> > >> > syzkaller hit the following crash on >> > 30a7acd573899fd8b8ac39236eff6468b195ac7d >> > git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.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+387f48da65cb522abfe8@xxxxxxxxxxxxxxxxxxxxxxxxx >> > 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. >> >> This looks ALSA-related. +ALSA maintainers. > > Not sure exactly what triggers it. It's the simple memcpy(), and I > don't know where RCU is involved in that code path. > > BTW, other two suspicious RCU usage reports are actually stopped at > the second WARN_ON() after the RCU message, and the second WARN_ON() > is independent from RCU; it's the known spurious WARN_ON() and was > already removed in the sound git tree. Hi Takashi, Another similar one just popped up: https://groups.google.com/forum/#!topic/syzkaller-bugs/X3d6-PIrJM0 This looks like mulaw_decode enters an infinite loop, or at least doing very large amount of computations without a resched, e.g. (uint64_t)-1 number of iterations of something along these lines. >> > INFO: rcu_sched detected stalls on CPUs/tasks: >> > (detected by 0, t=125002 jiffies, g=15654, c=15653, q=133) >> > All QSes seen, last rcu_sched kthread activity 125002 >> > (4294863411-4294738409), jiffies_till_next_fqs=3, root ->qsmask 0x0 >> > syz-executor1 R running task 24936 11943 3739 0x0000000c >> > Call Trace: >> > <IRQ> >> > sched_show_task+0x4a3/0x5e0 kernel/sched/core.c:5198 >> > print_other_cpu_stall+0x996/0x1090 kernel/rcu/tree.c:1564 >> > check_cpu_stall.isra.61+0x6e6/0x15b0 kernel/rcu/tree.c:1682 >> > __rcu_pending kernel/rcu/tree.c:3440 [inline] >> > rcu_pending kernel/rcu/tree.c:3502 [inline] >> > rcu_check_callbacks+0x256/0xd00 kernel/rcu/tree.c:2842 >> > 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:1194 >> > __run_hrtimer kernel/time/hrtimer.c:1211 [inline] >> > __hrtimer_run_queues+0x358/0xe20 kernel/time/hrtimer.c:1275 >> > hrtimer_interrupt+0x1c2/0x5e0 kernel/time/hrtimer.c:1309 >> > local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline] >> > smp_apic_timer_interrupt+0x14a/0x700 arch/x86/kernel/apic/apic.c:1050 >> > apic_timer_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:920 >> > </IRQ> >> > RIP: 0010:kasan_mem_to_shadow include/linux/kasan.h:30 [inline] >> > RIP: 0010:memory_is_poisoned_n mm/kasan/kasan.c:210 [inline] >> > RIP: 0010:memory_is_poisoned mm/kasan/kasan.c:241 [inline] >> > RIP: 0010:check_memory_region_inline mm/kasan/kasan.c:257 [inline] >> > RIP: 0010:check_memory_region+0x38/0x190 mm/kasan/kasan.c:267 >> > RSP: 0000:ffff8801bd2ff868 EFLAGS: 00000212 ORIG_RAX: ffffffffffffff11 >> > RAX: ffff7fffffffffff RBX: ffffc9000160020b RCX: ffffffff841fceaf >> > RDX: 0000000000000001 RSI: 0000000000000002 RDI: ffffc9000160020a >> > RBP: ffff8801bd2ff878 R08: ffffc9000160020a R09: dffffc0000000000 >> > R10: 0000000000000001 R11: ffffed0037a5ff2e R12: ffffc9000160020a >> > R13: ffff8801bd2ff970 R14: dffffc0000000000 R15: ffffc9000160020a >> > memcpy+0x37/0x50 mm/kasan/kasan.c:303 >> > memcpy include/linux/string.h:344 [inline] >> > cvt_s16_to_native sound/core/oss/mulaw.c:164 [inline] >> > mulaw_decode+0x52f/0x770 sound/core/oss/mulaw.c:195 >> > mulaw_transfer+0x222/0x270 sound/core/oss/mulaw.c:273 >> > snd_pcm_plug_write_transfer+0x22d/0x420 sound/core/oss/pcm_plugin.c:611 >> > snd_pcm_oss_write2+0x260/0x420 sound/core/oss/pcm_oss.c:1311 >> > snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1372 [inline] >> > snd_pcm_oss_write+0x5fe/0x830 sound/core/oss/pcm_oss.c:2646 >> > __vfs_write+0xef/0x970 fs/read_write.c:480 >> > vfs_write+0x189/0x510 fs/read_write.c:544 >> > SYSC_write fs/read_write.c:589 [inline] >> > SyS_write+0xef/0x220 fs/read_write.c:581 >> > entry_SYSCALL_64_fastpath+0x23/0x9a >> > RIP: 0033:0x452ac9 >> > RSP: 002b:00007fa354a13c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000001 >> > RAX: ffffffffffffffda RBX: cccccccccccccccd RCX: 0000000000452ac9 >> > RDX: 00000000fffffeb2 RSI: 0000000020083fc6 RDI: 0000000000000014 >> > RBP: 00000000000005b5 R08: 0000000000000000 R09: 0000000000000000 >> > R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f6998 >> > R13: 00000000ffffffff R14: 00007fa354a146d4 R15: 0000000000000000 >> > rcu_sched kthread starved for 125002 jiffies! g15654 c15653 f0x2 >> > RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=0 >> > rcu_sched R running task 23456 8 2 0x80000000 >> > Call Trace: >> > context_switch kernel/sched/core.c:2799 [inline] >> > __schedule+0x8eb/0x2060 kernel/sched/core.c:3375 >> > schedule+0xf5/0x430 kernel/sched/core.c:3434 >> > schedule_timeout+0x118/0x230 kernel/time/timer.c:1793 >> > rcu_gp_kthread+0x9e5/0x1930 kernel/rcu/tree.c:2314 >> > kthread+0x33c/0x400 kernel/kthread.c:238 >> > ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:524 >> > >> > >> > --- >> > This bug is generated by a dumb bot. It may contain errors. >> > See https://goo.gl/tpsmEJ for details. >> > Direct all questions to syzkaller@xxxxxxxxxxxxxxxx. >> > >> > 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@xxxxxxxxxxxxxxxx. >> > To view this discussion on the web visit >> > https://groups.google.com/d/msgid/syzkaller-bugs/001a113f711a23fe310561f21d1a%40google.com. >> > >> > For more options, visit https://groups.google.com/d/optout. >> _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
