Re: kernel BUG at arch/x86/kvm/mmu.c:LINE! (2)

[Paolo Bonzini]

#syz dup:  KASAN: slab-out-of-bounds Read in handle_vmptrld

On 08/11/19 20:14, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:ÂÂÂ 847120f8 Merge branch 'for-linus' of
> git://git.kernel.org/..
> git tree:ÂÂÂÂÂÂ upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=12d60164e00000
> kernel config:Â https://syzkaller.appspot.com/x/.config?x=8c5e2eca3f31f9bf
> dashboard link:
> https://syzkaller.appspot.com/bug?extid=824609cfabee9c6e153c
> compiler:ÂÂÂÂÂÂ gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:ÂÂÂÂÂ https://syzkaller.appspot.com/x/repro.syz?x=16e2a12ce00000
> C reproducer:ÂÂ https://syzkaller.appspot.com/x/repro.c?x=13314994e00000
> 
> The bug was bisected to:
> 
> commit 1ffe8bdc09f8bfcaad76d71ae68b623c7e03f20f
> Author: Spencer E. Olson <olsonse@xxxxxxxxx>
> Date:ÂÂ Mon Oct 10 14:14:19 2016 +0000
> 
> ÂÂÂ staging: comedi: ni_mio_common: split out ao arming from ni_ao_inttrig
> 
> bisection log:Â https://syzkaller.appspot.com/x/bisect.txt?x=122977fae00000
> console output: https://syzkaller.appspot.com/x/log.txt?x=162977fae00000
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+824609cfabee9c6e153c@xxxxxxxxxxxxxxxxxxxxxxxxx
> Fixes: 1ffe8bdc09f8 ("staging: comedi: ni_mio_common: split out ao
> arming from ni_ao_inttrig")
> 
> L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646
> and https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html
> for details.
> ------------[ cut here ]------------
> kernel BUG at arch/x86/kvm/mmu.c:3324!
> invalid opcode: 0000 [#1] PREEMPT SMP KASAN
> CPU: 0 PID: 8688 Comm: syz-executor906 Not tainted 5.4.0-rc6+ #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> RIP: 0010:transparent_hugepage_adjust+0x490/0x530 arch/x86/kvm/mmu.c:3324
> Code: 63 00 48 8b 45 b8 48 83 e8 01 e9 19 fd ff ff e8 36 3c 63 00 48 8b
> 45 b8 48 83 e8 01 48 89 45 c8 e9 a1 fd ff ff e8 20 3c 63 00 <0f> 0b 48
> 89 df e8 66 9e 9e 00 e9 9f fb ff ff 4c 89 ff e8 59 9e 9e
> RSP: 0018:ffff88809753f690 EFLAGS: 00010293
> RAX: ffff88809549e6c0 RBX: ffff88809753f778 RCX: ffffffff810fe787
> RDX: 0000000000000000 RSI: ffffffff810fe8c0 RDI: 0000000000000007
> RBP: ffff88809753f6d8 R08: ffff88809549e6c0 R09: ffffed10131ed682
> R10: ffffed10131ed681 R11: ffff888098f6b40b R12: ffff88809753f768
> R13: 0000000000000083 R14: 000000000008fe81 R15: 0000000000000000
> FS:Â 000000000158e880(0000) GS:ffff8880ae800000(0000)
> knlGS:0000000000000000
> CS:Â 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000000 CR3: 000000009f2a4000 CR4: 00000000001426f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> Âtdp_page_fault+0x56e/0x650 arch/x86/kvm/mmu.c:4216
> Âkvm_mmu_page_fault+0x1dd/0x1800 arch/x86/kvm/mmu.c:5439
> Âhandle_ept_violation+0x259/0x560 arch/x86/kvm/vmx/vmx.c:5185
> Âvmx_handle_exit+0x29f/0x1730 arch/x86/kvm/vmx/vmx.c:5929
> Âvcpu_enter_guest arch/x86/kvm/x86.c:8227 [inline]
> Âvcpu_run arch/x86/kvm/x86.c:8291 [inline]
> Âkvm_arch_vcpu_ioctl_run+0x1cb8/0x70d0 arch/x86/kvm/x86.c:8498
> Âkvm_vcpu_ioctl+0x4dc/0xfc0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2772
> Âvfs_ioctl fs/ioctl.c:46 [inline]
> Âfile_ioctl fs/ioctl.c:509 [inline]
> Âdo_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
> Âksys_ioctl+0xab/0xd0 fs/ioctl.c:713
> Â__do_sys_ioctl fs/ioctl.c:720 [inline]
> Â__se_sys_ioctl fs/ioctl.c:718 [inline]
> Â__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
> Âdo_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
> Âentry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x443f49
> 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 7b d8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007ffd991d67d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000443f49
> RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000006
> RBP: 00000000006ce018 R08: 00000000004002e0 R09: 00000000004002e0
> R10: 00000000004002e0 R11: 0000000000000246 R12: 0000000000401c50
> R13: 0000000000401ce0 R14: 0000000000000000 R15: 0000000000000000
> Modules linked in:
> ---[ end trace 911095bae56804bc ]---
> RIP: 0010:transparent_hugepage_adjust+0x490/0x530 arch/x86/kvm/mmu.c:3324
> Code: 63 00 48 8b 45 b8 48 83 e8 01 e9 19 fd ff ff e8 36 3c 63 00 48 8b
> 45 b8 48 83 e8 01 48 89 45 c8 e9 a1 fd ff ff e8 20 3c 63 00 <0f> 0b 48
> 89 df e8 66 9e 9e 00 e9 9f fb ff ff 4c 89 ff e8 59 9e 9e
> RSP: 0018:ffff88809753f690 EFLAGS: 00010293
> RAX: ffff88809549e6c0 RBX: ffff88809753f778 RCX: ffffffff810fe787
> RDX: 0000000000000000 RSI: ffffffff810fe8c0 RDI: 0000000000000007
> RBP: ffff88809753f6d8 R08: ffff88809549e6c0 R09: ffffed10131ed682
> R10: ffffed10131ed681 R11: ffff888098f6b40b R12: ffff88809753f768
> R13: 0000000000000083 R14: 000000000008fe81 R15: 0000000000000000
> FS:Â 000000000158e880(0000) GS:ffff8880ae800000(0000)
> knlGS:0000000000000000
> CS:Â 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000000 CR3: 000000009f2a4000 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
> 
> syzbot will keep track of this bug report. See:
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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