On Sun, Jun 12, 2022, syzbot wrote: > syzbot has found a reproducer for the following issue on: > > HEAD commit: 7a68065eb9cd Merge tag 'gpio-fixes-for-v5.19-rc2' of git:/.. > git tree: upstream > console+strace: https://syzkaller.appspot.com/x/log.txt?x=177df408080000 > kernel config: https://syzkaller.appspot.com/x/.config?x=20ac3e0ebf0db3bd > dashboard link: https://syzkaller.appspot.com/bug?extid=4688c50a9c8e68e7aaa1 > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12087173f00000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16529343f00000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+4688c50a9c8e68e7aaa1@xxxxxxxxxxxxxxxxxxxxxxxxx > > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 3609 at arch/x86/kvm/vmx/vmx.c:4896 handle_exception_nmi+0xfdc/0x1190 arch/x86/kvm/vmx/vmx.c:4896 > Modules linked in: > CPU: 0 PID: 3609 Comm: syz-executor169 Not tainted 5.19.0-rc1-syzkaller-00303-g7a68065eb9cd #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 I'm pretty sure this is a bug in GCE's L0 KVM. Per syzbot's bisection, the WARN repros all the way back to v5.11 on GCE. The test is doing VMWRITE from its L1 (effective L2) with a memory operand that takes a #PF. The #PF ends up in L1, which triggers the splat as KVM (real L1) isn't intercepting #PFs. I've repro'd this on a GCE host running a GCE kernel, and verified the same host running a v5.18 kernel does _not_ trigger the splat. I'll route this to someone internally. > RIP: 0010:handle_exception_nmi+0xfdc/0x1190 arch/x86/kvm/vmx/vmx.c:4896 > Code: 0f 84 c8 f3 ff ff e8 33 5c 58 00 48 89 ef c7 85 84 0d 00 00 00 00 00 00 e8 21 35 ec ff 41 89 c4 e9 af f3 ff ff e8 14 5c 58 00 <0f> 0b e9 69 f6 ff ff e8 08 5c 58 00 be f5 ff ff ff bf 01 00 00 00 > RSP: 0018:ffffc9000309faf8 EFLAGS: 00010293 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 > RDX: ffff88801ba1d880 RSI: ffffffff8122171c RDI: 0000000000000001 > RBP: ffff88807cd88000 R08: 0000000000000001 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000001 R12: 00000000a0000975 > R13: ffff88807cd88248 R14: 0000000000000000 R15: 0000000080000300 > FS: 0000555556c8d300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000000 CR3: 00000000229ca000 CR4: 00000000003526e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 00000000b8fecd19 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > <TASK> > __vmx_handle_exit arch/x86/kvm/vmx/vmx.c:6174 [inline] > vmx_handle_exit+0x498/0x1950 arch/x86/kvm/vmx/vmx.c:6191 > vcpu_enter_guest arch/x86/kvm/x86.c:10361 [inline] > vcpu_run arch/x86/kvm/x86.c:10450 [inline] > kvm_arch_vcpu_ioctl_run+0x4208/0x66f0 arch/x86/kvm/x86.c:10654 > kvm_vcpu_ioctl+0x570/0xf30 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3944 > vfs_ioctl fs/ioctl.c:51 [inline] > __do_sys_ioctl fs/ioctl.c:870 [inline] > __se_sys_ioctl fs/ioctl.c:856 [inline] > __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x46/0xb0 > RIP: 0033:0x7f56efaee199 > Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007ffc37353158 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f56efaee199 > RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005 > RBP: 00007f56efab1bf0 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00007f56efab1c80 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > </TASK> >
