Re: general protection fault in pvclock_gtod_notify (2)

[Dmitry Vyukov]

On Mon, Sep 21, 2020 at 10:10 AM Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
>
> On Mon, Sep 21, 2020 at 10:02 AM syzbot
> <syzbot+1dccfcb049726389379c@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> >
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:    eb5f95f1 Merge tag 's390-5.9-6' of git://git.kernel.org/pu..
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=14720ac3900000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=cd992d74d6c7e62
> > dashboard link: https://syzkaller.appspot.com/bug?extid=1dccfcb049726389379c
> > compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
> >
> > Unfortunately, I don't have any reproducer for this issue yet.
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+1dccfcb049726389379c@xxxxxxxxxxxxxxxxxxxxxxxxx
> >
> > general protection fault, probably for non-canonical address 0x1ffffffef40f602c: 0000 [#1] PREEMPT SMP KASAN
> > CPU: 1 PID: 3915 Comm: systemd-udevd Not tainted 5.9.0-rc5-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > RIP: 0010:update_pvclock_gtod arch/x86/kvm/x86.c:1743 [inline]
> > RIP: 0010:pvclock_gtod_notify+0x11d/0x490 arch/x86/kvm/x86.c:7452
> > Code: 10 48 89 f8 48 c1 e8 03 42 80 3c 20 00 74 05 e8 69 76 a7 00 49 8b 47 10 48 89 05 f6 08 cb 09 49 8d 7f 08 48 89 f8 48 c1 e8 03 <42> 80 3c 70 07 77 00 e8 47 76 a7 00 49 8b 47 08 48 89 05 dc 08 cb
> > RSP: 0018:ffffc90000da8c50 EFLAGS: 00010806
> > RAX: 1ffffffff1707d7e RBX: ffffffff894cc67c RCX: ffffffff815adc44
> > RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffffffff8b83ebf0
> > RBP: ffffffff894bd1a8 R08: dffffc0000000000 R09: fffffbfff167daa0
> > R10: fffffbfff167daa0 R11: 0000000000000000 R12: dffffc0000000000
> > R13: 00000000ffffffff R14: ffffffff814f7157 R15: ffffffff8b83ebe8
> > FS:  00007f7a9e2c88c0(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 0000000000744138 CR3: 00000000a256d000 CR4: 00000000001526e0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > Call Trace:
> >  <IRQ>
> >  notifier_call_chain kernel/notifier.c:83 [inline]
> >  __raw_notifier_call_chain kernel/notifier.c:361 [inline]
> >  raw_notifier_call_chain+0xe7/0x170 kernel/notifier.c:368
> >  update_pvclock_gtod kernel/time/timekeeping.c:581 [inline]
> >  timekeeping_update+0x281/0x3f0 kernel/time/timekeeping.c:675
> >  timekeeping_advance+0x830/0xa00 kernel/time/timekeeping.c:2122
> >  tick_sched_do_timer kernel/time/tick-sched.c:147 [inline]
> >  tick_sched_timer+0xba/0x410 kernel/time/tick-sched.c:1321
> >  __run_hrtimer kernel/time/hrtimer.c:1524 [inline]
> >  __hrtimer_run_queues+0x42d/0x930 kernel/time/hrtimer.c:1588
> >  hrtimer_interrupt+0x373/0xd60 kernel/time/hrtimer.c:1650
> >  local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1080 [inline]
> >  __sysvec_apic_timer_interrupt+0xf0/0x260 arch/x86/kernel/apic/apic.c:1097
> >  asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:706
> >  </IRQ>
> >  __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
> >  run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
> >  sysvec_apic_timer_interrupt+0x94/0xf0 arch/x86/kernel/apic/apic.c:1091
> >  asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:581
> > RIP: 0010:___might_sleep+0x60/0x570 kernel/sched/core.c:7265
> > Code: ff ff e8 e3 d2 d9 06 85 c0 74 1f c6 05 49 10 39 08 01 48 c7 c7 2a 87 09 89 be 61 1c 00 00 48 c7 c2 11 89 09 89 e8 90 a4 08 00 <e8> 4b d5 d9 06 85 c0 74 3d 80 3d 22 10 39 08 00 75 34 48 c7 c7 20
> > RSP: 0018:ffffc900011f7b08 EFLAGS: 00000246
> > RAX: 0000000000000000 RBX: 0000000000000c40 RCX: dffffc0000000000
> > RDX: 0000000000000000 RSI: ffffffff894fe578 RDI: 0000000000000282
> > RBP: ffff8880aa440900 R08: dffffc0000000000 R09: fffffbfff167da9f
> > R10: fffffbfff167da9f R11: 0000000000000000 R12: 0000000000001000
> > R13: 0000000000000c40 R14: 0000000000000000 R15: 0000000000000000
> >  cache_alloc_debugcheck_before mm/slab.c:2984 [inline]
> >  slab_alloc mm/slab.c:3302 [inline]
> >  __do_kmalloc mm/slab.c:3653 [inline]
> >  __kmalloc+0x94/0x300 mm/slab.c:3664
> >  kmalloc include/linux/slab.h:559 [inline]
> >  tomoyo_realpath_from_path+0xd8/0x630 security/tomoyo/realpath.c:254
> >  tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
> >  tomoyo_path_perm+0x17d/0x740 security/tomoyo/file.c:822
> >  security_inode_getattr+0xc0/0x140 security/security.c:1278
> >  vfs_getattr fs/stat.c:121 [inline]
> >  vfs_statx+0x118/0x380 fs/stat.c:206
> >  vfs_lstat include/linux/fs.h:3178 [inline]
> >  __do_sys_newlstat fs/stat.c:374 [inline]
> >  __se_sys_newlstat fs/stat.c:368 [inline]
> >  __x64_sys_newlstat+0x81/0xd0 fs/stat.c:368
> >  do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
> >  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> > RIP: 0033:0x7f7a9d13b335
> > Code: 69 db 2b 00 64 c7 00 16 00 00 00 b8 ff ff ff ff c3 0f 1f 40 00 83 ff 01 48 89 f0 77 30 48 89 c7 48 89 d6 b8 06 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 03 f3 c3 90 48 8b 15 31 db 2b 00 f7 d8 64 89
> > RSP: 002b:00007fff5eaa2608 EFLAGS: 00000246 ORIG_RAX: 0000000000000006
> > RAX: ffffffffffffffda RBX: 0000564636a00770 RCX: 00007f7a9d13b335
> > RDX: 00007fff5eaa2640 RSI: 00007fff5eaa2640 RDI: 00005646369ff770
> > RBP: 00007fff5eaa2700 R08: 00007f7a9d3fa178 R09: 0000000000001010
> > R10: 0000000000000020 R11: 0000000000000246 R12: 00005646369ff770
> > R13: 00005646369ff790 R14: 00005646369a42bb R15: 00005646369a42c0
> > Modules linked in:
> > ---[ end trace 4ff96b4858c23e64 ]---
> > RIP: 0010:update_pvclock_gtod arch/x86/kvm/x86.c:1743 [inline]
> > RIP: 0010:pvclock_gtod_notify+0x11d/0x490 arch/x86/kvm/x86.c:7452
> > Code: 10 48 89 f8 48 c1 e8 03 42 80 3c 20 00 74 05 e8 69 76 a7 00 49 8b 47 10 48 89 05 f6 08 cb 09 49 8d 7f 08 48 89 f8 48 c1 e8 03 <42> 80 3c 70 07 77 00 e8 47 76 a7 00 49 8b 47 08 48 89 05 dc 08 cb
> > RSP: 0018:ffffc90000da8c50 EFLAGS: 00010806
> > RAX: 1ffffffff1707d7e RBX: ffffffff894cc67c RCX: ffffffff815adc44
> > RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffffffff8b83ebf0
> > RBP: ffffffff894bd1a8 R08: dffffc0000000000 R09: fffffbfff167daa0
> > R10: fffffbfff167daa0 R11: 0000000000000000 R12: dffffc0000000000
> > R13: 00000000ffffffff R14: ffffffff814f7157 R15: ffffffff8b83ebe8
> > FS:  00007f7a9e2c88c0(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 0000000000744138 CR3: 00000000a256d000 CR4: 00000000001526e0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> >
> >
> > ---
> > This report is generated by a bot. It may contain errors.
> > See https://goo.gl/tpsmEJ for more information about syzbot.
> > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.
> >
> > syzbot will keep track of this issue. See:
> > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>
> The failure mode looks somewhat similar to:
> general protection fault in perf_misc_flags
> https://syzkaller.appspot.com/bug?extid=ce179bc99e64377c24bc
> https://groups.google.com/g/syzkaller-bugs/c/d5GC1V8S34k/m/6LTarP8mBAAJ
>
> only clang, gpf in systems code, happened few times

There is strong indication that this is a manifestation of the same
problem we see in other crashes.
Let's make one canonical bug for this:

#syz dup: general protection fault in perf_misc_flags