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Subjectkernel BUG at arch/x86/kvm/mmu/mmu.c:LINE! (2)
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Hello,

syzbot found the following crash on:

HEAD commit: c11d28ab Add linux-next specific files for 20200522
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=153b5016100000
kernel config: https://syzkaller.appspot.com/x/.config?x=3f6dbdea4159fb66
dashboard link: https://syzkaller.appspot.com/bug?extid=904752567107eefb728c
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11510cba100000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=129301e2100000

The bug was bisected to:

commit 63d04348371b7ea4a134bcf47c79763d969e9168
Author: Paolo Bonzini <pbonzini@redhat.com>
Date: Tue Mar 31 22:42:22 2020 +0000

KVM: x86: move kvm_create_vcpu_debugfs after last failure point

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1226e8ee100000
final crash: https://syzkaller.appspot.com/x/report.txt?x=1126e8ee100000
console output: https://syzkaller.appspot.com/x/log.txt?x=1626e8ee100000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+904752567107eefb728c@syzkaller.appspotmail.com
Fixes: 63d04348371b ("KVM: x86: move kvm_create_vcpu_debugfs after last failure point")

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/mmu.c:3722!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 6784 Comm: syz-executor805 Not tainted 5.7.0-rc6-next-20200522-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:mmu_alloc_direct_roots arch/x86/kvm/mmu/mmu.c:3722 [inline]
RIP: 0010:mmu_alloc_roots arch/x86/kvm/mmu/mmu.c:3822 [inline]
RIP: 0010:kvm_mmu_load+0xbfa/0xe00 arch/x86/kvm/mmu/mmu.c:5155
Code: 9c 5f 99 00 48 8b 44 24 08 e9 cf f5 ff ff e8 5d 5f 99 00 e9 b7 f4 ff ff 4c 89 f7 e8 80 5f 99 00 e9 78 f4 ff ff e8 16 4c 5a 00 <0f> 0b 48 89 df e8 6c 5f 99 00 e9 7e f8 ff ff e8 62 5f 99 00 e9 c4
RSP: 0018:ffffc90000f77b10 EFLAGS: 00010293
RAX: ffff8880a1348340 RBX: 0000000000000000 RCX: ffffffff81195061
RDX: 0000000000000000 RSI: ffffffff81195b4a RDI: 0000000000000001
RBP: ffff888095110040 R08: ffff8880a1348340 R09: ffffed1015cc717c
R10: ffff8880ae638bdb R11: ffffed1015cc717b R12: 0000000000000000
R13: 0000000000000001 R14: ffff888095110458 R15: 0000000000000000
FS: 0000000002160880(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa3dffa2010 CR3: 000000008fb39000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
kvm_mmu_reload arch/x86/kvm/mmu.h:81 [inline]
vcpu_enter_guest arch/x86/kvm/x86.c:8385 [inline]
vcpu_run arch/x86/kvm/x86.c:8596 [inline]
kvm_arch_vcpu_ioctl_run+0x4022/0x6920 arch/x86/kvm/x86.c:8819
kvm_vcpu_ioctl+0x46a/0xe20 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3149
vfs_ioctl fs/ioctl.c:48 [inline]
ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
__do_sys_ioctl fs/ioctl.c:762 [inline]
__se_sys_ioctl fs/ioctl.c:760 [inline]
__x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x4401f9
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 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffedfd41fc8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004401f9
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 00000000004002c8 R11: 0000000000000246 R12: 0000000000401a80
R13: 0000000000401b10 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace 2d2ab0eef7b13e8d ]---
RIP: 0010:mmu_alloc_direct_roots arch/x86/kvm/mmu/mmu.c:3722 [inline]
RIP: 0010:mmu_alloc_roots arch/x86/kvm/mmu/mmu.c:3822 [inline]
RIP: 0010:kvm_mmu_load+0xbfa/0xe00 arch/x86/kvm/mmu/mmu.c:5155
Code: 9c 5f 99 00 48 8b 44 24 08 e9 cf f5 ff ff e8 5d 5f 99 00 e9 b7 f4 ff ff 4c 89 f7 e8 80 5f 99 00 e9 78 f4 ff ff e8 16 4c 5a 00 <0f> 0b 48 89 df e8 6c 5f 99 00 e9 7e f8 ff ff e8 62 5f 99 00 e9 c4
RSP: 0018:ffffc90000f77b10 EFLAGS: 00010293
RAX: ffff8880a1348340 RBX: 0000000000000000 RCX: ffffffff81195061
RDX: 0000000000000000 RSI: ffffffff81195b4a RDI: 0000000000000001
RBP: ffff888095110040 R08: ffff8880a1348340 R09: ffffed1015cc717c
R10: ffff8880ae638bdb R11: ffffed1015cc717b R12: 0000000000000000
R13: 0000000000000001 R14: ffff888095110458 R15: 0000000000000000
FS: 0000000002160880(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa3dffa6000 CR3: 000000008fb39000 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@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
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

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