Re: [v5.15] WARNING in kvm_arch_vcpu_ioctl_run

[Muhammad Usama Anjum]

On 5/5/23 1:28 PM, syzbot wrote:
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit: 8a7f2a5c5aa1 Linux 5.15.110
This same warning has also been found on  6.1.21.

> git tree: linux-5.15.y
> console output: https://syzkaller.appspot.com/x/log.txt?x=15f12318280000
> kernel config: https://syzkaller.appspot.com/x/.config?x=ba8d5c9d6c5289f
> dashboard link: https://syzkaller.appspot.com/bug?extid=412c9ae97b4338c5187e
> compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10e13c84280000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=149d9470280000
I've tried all the C and syz reproducers. I've also tried syz-crash which
launched multiple instances of VMs and ran syz reproducer. But the issue
didn't get reproduced.

I don't have kvm skills. Can someone have a look at the the warning
(probably by static analysis)?

> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/fc04f54c047f/disk-8a7f2a5c.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/6b4ba4cb1191/vmlinux-8a7f2a5c.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/d927dc3f9670/bzImage-8a7f2a5c.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+412c9ae97b4338c5187e@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 3502 at arch/x86/kvm/x86.c:10310 kvm_arch_vcpu_ioctl_run+0x1d63/0x1f80
> Modules linked in:
> CPU: 1 PID: 3502 Comm: syz-executor306 Not tainted 5.15.110-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
> RIP: 0010:kvm_arch_vcpu_ioctl_run+0x1d63/0x1f80 arch/x86/kvm/x86.c:10310
> Code: df e8 71 ac b9 00 e9 e5 fa ff ff 89 d9 80 e1 07 38 c1 0f 8c 26 fb ff ff 48 89 df e8 57 ac b9 00 e9 19 fb ff ff e8 4d 52 70 00 <0f> 0b e9 e0 fb ff ff 89 d9 80 e1 07 38 c1 0f 8c 63 fb ff ff 48 89
> RSP: 0018:ffffc90002bcfc60 EFLAGS: 00010293
> RAX: ffffffff810f8c33 RBX: 0000000000000000 RCX: ffff888012bc1d00
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
> RBP: dffffc0000000000 R08: ffffffff8116a882 R09: fffffbfff1bc744e
> R10: 0000000000000000 R11: dffffc0000000001 R12: ffff888012bc1d00
> R13: ffff888077580000 R14: ffff8880775800f0 R15: ffff88801e2a9000
> FS: 000055555696f300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fafc4b53130 CR3: 000000007c8ce000 CR4: 00000000003526e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> <TASK>
> kvm_vcpu_ioctl+0x7f0/0xcf0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3863
> vfs_ioctl fs/ioctl.c:51 [inline]
> __do_sys_ioctl fs/ioctl.c:874 [inline]
> __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:860
> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
> entry_SYSCALL_64_after_hwframe+0x61/0xcb
> RIP: 0033:0x7fafc4ae1ed9
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 00 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffd3bb98a48 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 000000000000cdf3 RCX: 00007fafc4ae1ed9
> RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
> RBP: 0000000000000000 R08: 00007ffd3bb98be8 R09: 00007ffd3bb98be8
> R10: 00007ffd3bb98be8 R11: 0000000000000246 R12: 00007ffd3bb98a5c
> R13: 431bde82d7b634db R14: 0000000000000000 R15: 0000000000000000
> </TASK>
> 
> 
> ---
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
> 

-- 
BR,
Muhammad Usama Anjum