Re: BUG: corrupted list in vmx_vcpu_load

From: Dmitry Vyukov
Date: Wed Feb 20 2019 - 11:59:45 EST

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On Wed, Aug 22, 2018 at 8:28 AM syzbot
<syzbot+bba49d73fe3404646a7b@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: 0214f46b3a03 Merge branch 'siginfo-linus' of git://git.ker..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11bc9c2e400000
> kernel config: https://syzkaller.appspot.com/x/.config?x=214e4990bd49329f
> dashboard link: https://syzkaller.appspot.com/bug?extid=bba49d73fe3404646a7b
> compiler: gcc (GCC) 8.0.1 20180413 (experimental)
>
> Unfortunately, I don't have any reproducer for this crash yet.
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+bba49d73fe3404646a7b@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> kvm [9433]: vcpu0, guest rIP: 0x20e disabled perfctr wrmsr: 0x187 data
> 0x60000000800
> list_add corruption. next->prev should be prev (ffff8801db01d130), but was
> dead000000000200. (next=ffff8801947fdaa0).
> ------------[ cut here ]------------
> kernel BUG at lib/list_debug.c:25!
> invalid opcode: 0000 [#1] SMP KASAN
> CPU: 0 PID: 9519 Comm: syz-executor2 Not tainted 4.18.0+ #201
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> RIP: 0010:__list_add_valid.cold.0+0xf/0x25 lib/list_debug.c:23
> Code: e8 93 f5 5b fe e9 68 ff ff ff e8 89 f5 5b fe eb c9 4c 89 e7 e8 7f f5
> 5b fe eb 97 48 89 d9 48 c7 c7 e0 9b 3a 87 e8 32 d8 03 fe <0f> 0b 48 89 f1
> 48 c7 c7 a0 9c 3a 87 48 89 de e8 1e d8 03 fe 0f 0b
> RSP: 0018:ffff88018f9bf058 EFLAGS: 00010082
> RAX: 0000000000000075 RBX: ffff8801947fdaa0 RCX: ffffc9000200d000
> RDX: 0000000000000000 RSI: ffffffff8163a441 RDI: 0000000000000001
> RBP: ffff88018f9bf070 R08: ffff880196e3a2c0 R09: ffffed003b605008
> R10: ffffed003b605008 R11: ffff8801db028047 R12: ffff8801947fdaa0
> R13: ffff8801947f8300 R14: ffff8801947fdaa0 R15: ffff8801db01d130
> FS: 00007ff35b75e700(0000) GS:ffff8801db000000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fcb6c09b000 CR3: 00000001ca309000 CR4: 00000000001426f0
> Call Trace:
> __list_add include/linux/list.h:60 [inline]
> list_add include/linux/list.h:79 [inline]
> vmx_vcpu_load+0x205/0xfe0 arch/x86/kvm/vmx.c:3061

Let's do:

#syz dup: KASAN: use-after-free Read in vmx_vcpu_load

Both are in the same function and appeared roughly at the same time.

> kvm_arch_vcpu_load+0x22b/0x940 arch/x86/kvm/x86.c:3106
> kvm_sched_in+0x82/0xa0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3970
> __fire_sched_in_preempt_notifiers kernel/sched/core.c:2481 [inline]
> fire_sched_in_preempt_notifiers kernel/sched/core.c:2487 [inline]
> finish_task_switch+0x50d/0x870 kernel/sched/core.c:2679
> context_switch kernel/sched/core.c:2828 [inline]
> __schedule+0x884/0x1df0 kernel/sched/core.c:3473
> preempt_schedule_common+0x22/0x60 kernel/sched/core.c:3597
> _cond_resched+0x1d/0x30 kernel/sched/core.c:4963
> slab_pre_alloc_hook mm/slab.h:421 [inline]
> slab_alloc mm/slab.c:3378 [inline]
> kmem_cache_alloc+0x292/0x710 mm/slab.c:3552
> alloc_inode+0xb2/0x190 fs/inode.c:212
> new_inode_pseudo+0x71/0x1a0 fs/inode.c:903
> new_inode+0x1c/0x40 fs/inode.c:932
> debugfs_get_inode+0x19/0x120 fs/debugfs/inode.c:37
> __debugfs_create_file+0xb5/0x400 fs/debugfs/inode.c:352
> debugfs_create_file+0x57/0x70 fs/debugfs/inode.c:399
> kvm_create_vm_debugfs arch/x86/kvm/../../../virt/kvm/kvm_main.c:615
> [inline]
> kvm_dev_ioctl_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:3209
> [inline]
> kvm_dev_ioctl+0xbf5/0x1b10 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3236
> vfs_ioctl fs/ioctl.c:46 [inline]
> file_ioctl fs/ioctl.c:500 [inline]
> do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:684
> ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701
> __do_sys_ioctl fs/ioctl.c:708 [inline]
> __se_sys_ioctl fs/ioctl.c:706 [inline]
> __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706
> do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x457089
> Code: fd b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007ff35b75dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 00007ff35b75e6d4 RCX: 0000000000457089
> RDX: 0000000000000000 RSI: 000000000000ae01 RDI: 0000000000000006
> RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
> R13: 00000000004ce9b8 R14: 00000000004c50d7 R15: 0000000000000000
> Modules linked in:
> Dumping ftrace buffer:
> (ftrace buffer empty)
> ---[ end trace a4f093c8080a0418 ]---
> RIP: 0010:__list_add_valid.cold.0+0xf/0x25 lib/list_debug.c:23
> Code: e8 93 f5 5b fe e9 68 ff ff ff e8 89 f5 5b fe eb c9 4c 89 e7 e8 7f f5
> 5b fe eb 97 48 89 d9 48 c7 c7 e0 9b 3a 87 e8 32 d8 03 fe <0f> 0b 48 89 f1
> 48 c7 c7 a0 9c 3a 87 48 89 de e8 1e d8 03 fe 0f 0b
> RSP: 0018:ffff88018f9bf058 EFLAGS: 00010082
> RAX: 0000000000000075 RBX: ffff8801947fdaa0 RCX: ffffc9000200d000
> RDX: 0000000000000000 RSI: ffffffff8163a441 RDI: 0000000000000001
> RBP: ffff88018f9bf070 R08: ffff880196e3a2c0 R09: ffffed003b605008
> R10: ffffed003b605008 R11: ffff8801db028047 R12: ffff8801947fdaa0
> R13: ffff8801947f8300 R14: ffff8801947fdaa0 R15: ffff8801db01d130
> FS: 00007ff35b75e700(0000) GS:ffff8801db000000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fcb6c09b000 CR3: 00000001ca309000 CR4: 00000000001426f0
>
>
> ---
> 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:
> https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
> syzbot.
>
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Next message: Andrey Ryabinin: "Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier"
Previous message: Dmitry Vyukov: "Re: general protection fault in lockref_get"
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