Re: WARNING in kvm_arch_vcpu_ioctl_run (3)

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit:    1d2ba7fee28b Merge tag 'fbdev-v4.19-rc7' of https://github..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15b019b9400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c0af03fe452b65fb
dashboard link: https://syzkaller.appspot.com/bug?extid=760a73552f47a8cd0fd9
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=156ad231400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+760a73552f47a8cd0fd9@xxxxxxxxxxxxxxxxxxxxxxxxx

kvm: emulating exchange as write
WARNING: CPU: 1 PID: 10797 at arch/x86/kvm/x86.c:7925  
kvm_arch_vcpu_ioctl_run+0x1ca/0x16e0 arch/x86/kvm/x86.c:7925
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 10797 Comm: syz-executor4 Not tainted 4.19.0-rc6+ #264
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113
 panic+0x238/0x4e7 kernel/panic.c:184
 __warn.cold.8+0x163/0x1ba kernel/panic.c:536
 report_bug+0x254/0x2d0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x1fc/0x4d0 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:993
RIP: 0010:kvm_arch_vcpu_ioctl_run+0x1ca/0x16e0 arch/x86/kvm/x86.c:7925
Code: 03 80 3c 02 00 0f 85 f0 13 00 00 4c 8b a3 18 2c 00 00 31 ff 4c 89 e6  
e8 74 96 6e 00 4d 85 e4 0f 84 fd 0a 00 00 e8 36 95 6e 00 <0f> 0b e8 2f 95  
6e 00 49 8d 7d 01 48 b8 00 00 00 00 00 fc ff df 48
RSP: 0018:ffff8801d7fff860 EFLAGS: 00010293
RAX: ffff8801c92de280 RBX: ffff8801c8fe0540 RCX: ffffffff81102b80
RDX: 0000000000000000 RSI: ffffffff8110204a RDI: 0000000000000005
RBP: ffff8801d7fff8d8 R08: ffff8801c92de280 R09: 1ffffffff1273955
R10: ffffed003b5e4732 R11: ffff8801daf23993 R12: 0000000000000001
R13: ffff8801c29a7000 R14: 0000000000000000 R15: ffff8801c8fe0618
 kvm_vcpu_ioctl+0x72b/0x1150 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2590
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
 __do_sys_ioctl fs/ioctl.c:709 [inline]
 __se_sys_ioctl fs/ioctl.c:707 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457579
Code: 1d 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 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f51c3ee0c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457579
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 000000000072c040 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f51c3ee16d4
R13: 00000000004c003b R14: 00000000004d0108 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..