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Date: Thu, 29 Mar 2018 12:32:25 -0400
From: Steven Rostedt <rostedt@goodmis.org>
To: syzbot <syzbot+d1fe9b7b917f2715c7d4@syzkaller.appspotmail.com>
Cc: linux-kernel@vger.kernel.org, pmladek@suse.com,
        sergey.senozhatsky@gmail.com, syzkaller-bugs@googlegroups.com
Subject: Re: general protection fault in try_to_wake_up
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Not sure why we are being Cc'd on this crash.

On Thu, 29 Mar 2018 09:01:02 -0700
syzbot <syzbot+d1fe9b7b917f2715c7d4@syzkaller.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@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.
> 
> 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.

-- Steve


> 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.
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