Re: general protection fault in __apic_accept_irq

[Wanpeng Li]

On Thu, 5 Sep 2019 at 16:53, syzbot
<syzbot+dff25ee91f0c7d5c1695@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    3b47fd5c Merge tag 'nfs-for-5.3-4' of git://git.linux-nfs...
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=124af12a600000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=144488c6c6c6d2b6
> dashboard link: https://syzkaller.appspot.com/bug?extid=dff25ee91f0c7d5c1695
> compiler:       clang version 9.0.0 (/home/glider/llvm/clang
> 80fee25776c2fb61e74c1ecb1a523375c2500b69)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10954676600000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1752fe0a600000
>
> The bug was bisected to:
>
> commit 0aa67255f54df192d29aec7ac6abb1249d45bda7
> Author: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> Date:   Mon Nov 26 15:47:29 2018 +0000
>
>      x86/hyper-v: move synic/stimer control structures definitions to
> hyperv-tlfs.h
>
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=156128c1600000
> console output: https://syzkaller.appspot.com/x/log.txt?x=136128c1600000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+dff25ee91f0c7d5c1695@xxxxxxxxxxxxxxxxxxxxxxxxx
> Fixes: 0aa67255f54d ("x86/hyper-v: move synic/stimer control structures
> definitions to hyperv-tlfs.h")
>
> kvm [9347]: vcpu0, guest rIP: 0xcc Hyper-V uhandled wrmsr: 0x40000004 data
> 0x94
> kvm [9347]: vcpu0, guest rIP: 0xcc Hyper-V uhandled wrmsr: 0x40000004 data
> 0x48c
> kvm [9347]: vcpu0, guest rIP: 0xcc Hyper-V uhandled wrmsr: 0x40000004 data
> 0x4ac
> kvm [9347]: vcpu0, guest rIP: 0xcc Hyper-V uhandled wrmsr: 0x40000005 data
> 0x1520
> kvm [9347]: vcpu0, guest rIP: 0xcc Hyper-V uhandled wrmsr: 0x40000006 data
> 0x15d4
> kvm [9347]: vcpu0, guest rIP: 0xcc Hyper-V uhandled wrmsr: 0x40000007 data
> 0x15c4
> kasan: CONFIG_KASAN_INLINE enabled
> kasan: GPF could be caused by NULL-ptr deref or user memory access
> general protection fault: 0000 [#1] PREEMPT SMP KASAN
> CPU: 0 PID: 9347 Comm: syz-executor665 Not tainted 5.3.0-rc7+ #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> RIP: 0010:__apic_accept_irq+0x46/0x740 arch/x86/kvm/lapic.c:1029

Thanks for the report, I found the root cause, will send a patch soon.

> Code: 89 55 cc 41 89 f4 48 89 fb 49 bd 00 00 00 00 00 fc ff df e8 5c c9 5d
> 00 48 89 5d c0 4c 8d b3 98 00 00 00 4d 89 f7 49 c1 ef 03 <43> 80 3c 2f 00
> 74 08 4c 89 f7 e8 6b c4 96 00 49 8b 06 48 89 45 d0
> RSP: 0018:ffff88808a30f9b0 EFLAGS: 00010202
> RAX: ffffffff8115c384 RBX: 0000000000000000 RCX: ffff8880977f2140
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: ffff88808a30fa10 R08: 0000000000000000 R09: 0000000000000000
> R10: ffffed1011461f64 R11: 0000000000000000 R12: 0000000000000000
> R13: dffffc0000000000 R14: 0000000000000098 R15: 0000000000000013
> FS:  0000555555e35880(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000000 CR3: 000000008f96d000 CR4: 00000000001426f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>   kvm_apic_set_irq+0xb4/0x140 arch/x86/kvm/lapic.c:558
>   stimer_notify_direct arch/x86/kvm/hyperv.c:648 [inline]
>   stimer_expiration arch/x86/kvm/hyperv.c:659 [inline]
>   kvm_hv_process_stimers+0x594/0x1650 arch/x86/kvm/hyperv.c:686
>   vcpu_enter_guest+0x2b2a/0x54b0 arch/x86/kvm/x86.c:7896
>   vcpu_run+0x393/0xd40 arch/x86/kvm/x86.c:8152
>   kvm_arch_vcpu_ioctl_run+0x636/0x900 arch/x86/kvm/x86.c:8360
>   kvm_vcpu_ioctl+0x6cf/0xaf0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2765
>   do_vfs_ioctl+0x744/0x1730 fs/ioctl.c:46
>   ksys_ioctl fs/ioctl.c:713 [inline]
>   __do_sys_ioctl fs/ioctl.c:720 [inline]
>   __se_sys_ioctl fs/ioctl.c:718 [inline]
>   __x64_sys_ioctl+0xe3/0x120 fs/ioctl.c:718
>   do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:296
>   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x442a19
> Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> ff 0f 83 1b 0c fc ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007ffca3d2a208 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000442a19
> RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
> RBP: 00000000006cd018 R08: 00000000004002c8 R09: 00000000004002c8
> R10: 00000000004002c8 R11: 0000000000000246 R12: 0000000000403ac0
> R13: 0000000000403b50 R14: 0000000000000000 R15: 0000000000000000
> Modules linked in:
> ---[ end trace 8515c4c18eb55117 ]---
> RIP: 0010:__apic_accept_irq+0x46/0x740 arch/x86/kvm/lapic.c:1029
> Code: 89 55 cc 41 89 f4 48 89 fb 49 bd 00 00 00 00 00 fc ff df e8 5c c9 5d
> 00 48 89 5d c0 4c 8d b3 98 00 00 00 4d 89 f7 49 c1 ef 03 <43> 80 3c 2f 00
> 74 08 4c 89 f7 e8 6b c4 96 00 49 8b 06 48 89 45 d0
> RSP: 0018:ffff88808a30f9b0 EFLAGS: 00010202
> RAX: ffffffff8115c384 RBX: 0000000000000000 RCX: ffff8880977f2140
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: ffff88808a30fa10 R08: 0000000000000000 R09: 0000000000000000
> R10: ffffed1011461f64 R11: 0000000000000000 R12: 0000000000000000
> R13: dffffc0000000000 R14: 0000000000000098 R15: 0000000000000013
> FS:  0000555555e35880(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000000 CR3: 000000008f96d000 CR4: 00000000001426f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>
>
> ---
> This bug 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@xxxxxxxxxxxxxxxxx
>
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> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
> syzbot can test patches for this bug, for details see:
> https://goo.gl/tpsmEJ#testing-patches