Message-ID: <CACT4Y+ZJ2QD7MPy4hB-M=mz2LuVu3bRbLg1QdY=z=+Su1QWMqg@mail.gmail.com>
Date:   Thu, 29 Mar 2018 18:53:24 +0200
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     syzbot <syzbot+d1fe9b7b917f2715c7d4@...kaller.appspotmail.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        syzkaller-bugs@...glegroups.com, Eric Dumazet <edumazet@...gle.com>
Subject: Re: general protection fault in try_to_wake_up

On Thu, Mar 29, 2018 at 6:32 PM, Steven Rostedt <rostedt@...dmis.org> wrote:
>
> Not sure why we are being Cc'd on this crash.
>
> On Thu, 29 Mar 2018 09:01:02 -0700
> syzbot <syzbot+d1fe9b7b917f2715c7d4@...kaller.appspotmail.com> wrote:
>
>> Hello,
>>
>> syzbot hit the following crash on upstream commit
>> bcfc1f4554662d8f2429ac8bd96064a59c149754 (Sat Mar 24 16:50:12 2018 +0000)
>> Merge tag 'pinctrl-v4.16-3' of
>> git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl
>> syzbot dashboard link:
>> https://syzkaller.appspot.com/bug?extid=d1fe9b7b917f2715c7d4
>>
>> syzkaller reproducer:
>> https://syzkaller.appspot.com/x/repro.syz?id=4649457446551552
>> Raw console output:
>> https://syzkaller.appspot.com/x/log.txt?id=4909621332410368
>> Kernel config:
>> https://syzkaller.appspot.com/x/.config?id=-5034017172441945317
>> compiler: gcc (GCC) 7.1.1 20170620
>>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: syzbot+d1fe9b7b917f2715c7d4@...kaller.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.
>>
>> IPVS: ftp: loaded support on port[0] = 21
>> kasan: CONFIG_KASAN_INLINE enabled
>> kasan: GPF could be caused by NULL-ptr deref or user memory access
>> kasan: CONFIG_KASAN_INLINE enabled
>> kasan: GPF could be caused by NULL-ptr deref or user memory access
>> general protection fault: 0000 [#1] SMP KASAN
>> Dumping ftrace buffer:
>>     (ftrace buffer empty)
>> Modules linked in:
>> CPU: 0 PID: 4170 Comm: syz-executor0 Not tainted 4.16.0-rc6+ #1
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
>> Google 01/01/2011
>> RIP: 0010:__lock_acquire+0x209/0x3e00 kernel/locking/lockdep.c:3320
>
> Something is totally messed up here if you took a GPF in lockdep itself.
>
>> RSP: 0018:ffff8801db206f60 EFLAGS: 00010002
>> RAX: 078e0401078e0401 RBX: 0000000000000000 RCX: 0000000000000000
>> RDX: 1ffff100389fe583 RSI: 0000000000000000 RDI: ffff8801c4ff2c18
>> RBP: ffff8801db2072f0 R08: ffffffff814d839c R09: 0000000000000001
>> R10: 0000000000000000 R11: ffff8801c4ff2c10 R12: 0000000000000000
>> R13: 0000000000000001 R14: 0000000000000000 R15: ffff8801b793c440
>> FS:  00000000014fa940(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 00000000004cb4e0 CR3: 00000001b7980002 CR4: 00000000001606f0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> Call Trace:
>>   <IRQ>
>>   lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920
>>   __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
>>   _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152
>>   try_to_wake_up+0xbc/0x15f0 kernel/sched/core.c:1989
>>   default_wake_function+0x30/0x50 kernel/sched/core.c:3693
>>   autoremove_wake_function+0x78/0x350 kernel/sched/wait.c:377
>>   __wake_up_common+0x18e/0x780 kernel/sched/wait.c:97
>>   __wake_up_common_lock+0x1b4/0x310 kernel/sched/wait.c:125
>>   __wake_up+0xe/0x10 kernel/sched/wait.c:149
>>   wake_up_klogd_work_func+0x4a/0x70 kernel/printk/printk.c:2869
>>   irq_work_run_list+0x184/0x240 kernel/irq_work.c:155
>>   irq_work_tick+0x136/0x1a0 kernel/irq_work.c:181
>>   update_process_times+0x48/0x60 kernel/time/timer.c:1639
>>   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:1349 [inline]
>>   __hrtimer_run_queues+0x39c/0xec0 kernel/time/hrtimer.c:1411
>>   hrtimer_interrupt+0x2a5/0x6f0 kernel/time/hrtimer.c:1469
>>   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+0xf/0x20 arch/x86/entry/entry_64.S:857
>>   </IRQ>
>> RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:778
>> [inline]
>> RIP: 0010:console_unlock+0xb18/0xfb0 kernel/printk/printk.c:2403
>
> Perhaps this is the reason we are being Cc'd?
>
> But this looks to be a side-effect of the first bug. If your box is
> crashing within lockdep, I'm betting the system is hosed, and you will
> get crashes in random locations after that.
>
> I doubt this is a printk issue.

Hi Steven,

You were CCed because this crash was attributed to
kernel/printk/printk.c (higher frames are in very common code, and
these are skipped for the purpose of bug attribution).

The box was perfectly fine before running the provided reproducer, the
kernel is not tainted and nothing was executed before this program
(except for common init code).

+Eric, from the reproducer this looks like the known bug in tun. Is
there any progress on that bug, it seems to cause a bunch of assorted
crashes.



>> RSP: 0018:ffff8801b79068d8 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff12
>> RAX: ffff8801b793c440 RBX: 0000000000000200 RCX: ffffffff815a8d6f
>> RDX: 0000000000000000 RSI: 1ffff10036f279af RDI: 0000000000000293
>> RBP: ffff8801b7906a40 R08: 1ffff10036f20ce9 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
>> R13: 0000000000000000 R14: ffffffff83ba15e0 R15: dffffc0000000000
>>   vprintk_emit+0x5c3/0xb90 kernel/printk/printk.c:1907
>>   vprintk_default+0x28/0x30 kernel/printk/printk.c:1947
>>   vprintk_func+0x57/0xc0 kernel/printk/printk_safe.c:379
>>   printk+0xaa/0xca kernel/printk/printk.c:1980
>>   kasan_die_handler+0x3d/0x3f arch/x86/mm/kasan_init_64.c:248
>>   notifier_call_chain+0x136/0x2c0 kernel/notifier.c:93
>>   __atomic_notifier_call_chain kernel/notifier.c:183 [inline]
>>   atomic_notifier_call_chain+0x77/0x140 kernel/notifier.c:193
>>   notify_die+0x18c/0x280 kernel/notifier.c:549
>>   do_general_protection+0x331/0x3e0 arch/x86/kernel/traps.c:558
>>   general_protection+0x25/0x50 arch/x86/entry/entry_64.S:1150
>> RIP: 0010:find_entry.isra.14+0x9f/0x1d0 fs/proc/proc_sysctl.c:119
>> RSP: 0018:ffff8801b7906fc8 EFLAGS: 00010202
>> RAX: 00f1c08020f1c080 RBX: ffff8801c4f95058 RCX: ffffffff81d29eae
>> RDX: 0000000000000000 RSI: ffff8801b8991678 RDI: ffff8801c4f95070
>> RBP: ffff8801b7907008 R08: 1ffff10036f20d55 R09: 0000000000000004
>> R10: ffff8801b7906f70 R11: 0000000000000000 R12: ffff8801b89915f8
>> R13: dffffc0000000000 R14: 078e0401078e0401 R15: ffff8801b8991678
>>   find_subdir+0xa8/0x170 fs/proc/proc_sysctl.c:923
>>   get_subdir fs/proc/proc_sysctl.c:977 [inline]
>>   __register_sysctl_table+0x6d5/0x10b0 fs/proc/proc_sysctl.c:1327
>>   register_net_sysctl+0x29/0x30 net/sysctl_net.c:120
>>   mpls_dev_sysctl_register+0x1cf/0x2e0 net/mpls/af_mpls.c:1369
>>   mpls_add_dev net/mpls/af_mpls.c:1420 [inline]
>>   mpls_dev_notify+0x2af/0x980 net/mpls/af_mpls.c:1542
>>   notifier_call_chain+0x136/0x2c0 kernel/notifier.c:93
>>   __raw_notifier_call_chain kernel/notifier.c:394 [inline]
>>   raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
>>   call_netdevice_notifiers_info+0x32/0x70 net/core/dev.c:1707
>>   call_netdevice_notifiers net/core/dev.c:1725 [inline]
>>   register_netdevice+0xd40/0x1020 net/core/dev.c:7929
>>   register_netdev+0x1a/0x30 net/core/dev.c:8014
>>   sit_init_net+0x384/0xa70 net/ipv6/sit.c:1852
>>   ops_init+0x10a/0x570 net/core/net_namespace.c:118
>>   setup_net+0x351/0x760 net/core/net_namespace.c:302
>>   copy_net_ns+0x238/0x580 net/core/net_namespace.c:426
>>   create_new_namespaces+0x425/0x880 kernel/nsproxy.c:107
>>   unshare_nsproxy_namespaces+0xae/0x1e0 kernel/nsproxy.c:206
>>   SYSC_unshare kernel/fork.c:2407 [inline]
>>   SyS_unshare+0x653/0xfa0 kernel/fork.c:2357
>>   do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
>>   entry_SYSCALL_64_after_hwframe+0x42/0xb7
>> RIP: 0033:0x457327
>> RSP: 002b:00007ffdd0bf1928 EFLAGS: 00000202 ORIG_RAX: 0000000000000110
>> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000457327
>> RDX: 0000000000000000 RSI: 00007ffdd0bf1900 RDI: 0000000040000000
>> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001
>> R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000410710
>> R13: 00000000004107a0 R14: 0000000000000000 R15: 0000000000000000
>> Code: 48 85 c0 4c 8b 9d e8 fc ff ff 8b 8d e0 fc ff ff 44 8b 8d d8 fc ff ff
>> 4c 8b 85 d0 fc ff ff 44 8b 95 c8 fc ff ff 0f 84 9b 07 00 00 <f0> ff 80 38
>> 01 00 00 49 8d bf 70 08 00 00 48 ba 00 00 00 00 00
>> RIP: __lock_acquire+0x209/0x3e00 kernel/locking/lockdep.c:3320 RSP:
>> ffff8801db206f60
>> ---[ end trace b962f2b4a8ee2930 ]---
>>
>>
>> ---
>> This bug is generated by a dumb bot. It may contain errors.
>> See https://goo.gl/tpsmEJ for details.
>> Direct all questions to syzkaller@...glegroups.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
>> If you want to test a patch for this bug, please reply with:
>> #syz test: git://repo/address.git branch
>> and provide the patch inline or as an attachment.
>> 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:
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>> 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.
>
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