WARNING in kvm_arch_vcpu_ioctl_run

Status: fixed on 2025/10/19 16:15
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+763b05564bdd61631084@syzkaller.appspotmail.com
Fix commit: e750f8539128 KVM: x86: Don't (re)check L1 intercepts when completing userspace I/O
First crash: 319d, last: 319d
Fix bisection: fixed by (bisect log) :
commit 3d3abf3f7e8b1abb082070a343de82d7efc80523
Author: Sean Christopherson <seanjc@google.com>
Date: Tue Jul 15 19:06:38 2025 +0000

  KVM: x86: Don't (re)check L1 intercepts when completing userspace I/O

  
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2025/09/18 upstream (ToT) cbf658dd0941 C [report] WARNING in kvm_arch_vcpu_ioctl_run
▶ ▼ Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in kvm_arch_vcpu_ioctl_run (5) kvm-x86 -1 syz, C error 343 1054d 1142d 23/29 fixed on 2023/10/12 12:47
upstream WARNING in kvm_arch_vcpu_ioctl_run (4) kvm-x86 -1 syz, C error 288 1147d 1230d 22/29 fixed on 2023/06/08 14:41
upstream WARNING in kvm_arch_vcpu_ioctl_run (2) kvm-x86 -1 syz, C 61018 3102d 3191d 4/29 fixed on 2018/03/13 09:44
upstream WARNING in kvm_arch_vcpu_ioctl_run (6) kvm-x86 -1 syz, C 117 295d 376d 29/29 fixed on 2025/10/29 21:02
upstream WARNING in kvm_arch_vcpu_ioctl_run -1 syz, C 20284 3228d 3293d 3/29 fixed on 2017/09/26 01:38
linux-4.14 WARNING in kvm_arch_vcpu_ioctl_run -1 syz, C inconclusive 71 1413d 2590d 0/1 upstream: reported C repro on 2019/06/25 23:07
upstream WARNING in kvm_arch_vcpu_ioctl_run (3) kvm-x86 -1 syz, C done error 16157 1251d 3044d 22/29 fixed on 2023/02/24 13:50
linux-4.19 WARNING in kvm_arch_vcpu_ioctl_run -1 syz, C error 116 1323d 2598d 0/1 upstream: reported C repro on 2019/06/17 10:07
linux-5.15 WARNING in kvm_arch_vcpu_ioctl_run origin:lts-only -1 syz, C inconclusive 2025 11h13m 1207d 0/3 upstream: reported C repro on 2023/04/09 03:02
android-6-12 WARNING in kvm_arch_vcpu_ioctl_run origin:upstream -1 syz, C 51 275d 377d 0/1 premoderation: reported C repro on 2025/07/17 01:43
linux-6.1 WARNING in kvm_arch_vcpu_ioctl_run origin:lts-only -1 syz, C done 1564 2d20h 1223d 0/3 upstream: reported C repro on 2023/03/23 13:22

Sample crash report:
kvm_intel: 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 ]------------
WARNING: CPU: 0 PID: 5941 at arch/x86/kvm/x86.c:11233 kvm_arch_vcpu_ioctl_run+0xfdc/0x16a0 arch/x86/kvm/x86.c:11233
Modules linked in:
CPU: 0 PID: 5941 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:kvm_arch_vcpu_ioctl_run+0xfdc/0x16a0 arch/x86/kvm/x86.c:11233
Code: bf 01 00 00 00 89 c6 e8 82 8c 74 00 45 85 f6 7e 46 e8 c8 88 74 00 49 bd 00 00 00 00 00 fc ff df e9 0a fe ff ff e8 b4 88 74 00 <0f> 0b e9 c7 fd ff ff e8 a8 88 74 00 0f 0b e9 f2 fd ff ff e8 9c 88
RSP: 0018:ffffc900032d7a40 EFLAGS: 00010293
RAX: ffffffff8111078c RBX: ffff888026310000 RCX: ffff88802d2dbc00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900032d7d10 R08: dffffc0000000000 R09: 1ffffffff21b4ebc
R10: dffffc0000000000 R11: fffffbfff21b4ebd R12: 1ffff11004c62124
R13: dffffc0000000000 R14: 0000000000000001 R15: ffff88801b77d000
FS:  000055556f133500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000005200000c CR3: 000000001fb4d000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 kvm_vcpu_ioctl+0x88b/0xb80 virt/kvm/kvm_main.c:4162
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f97d058eba9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff535a8978 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f97d07d5fa0 RCX: 00007f97d058eba9
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 00007f97d0611e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f97d07d5fa0 R14: 00007f97d07d5fa0 R15: 0000000000000003
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/13 05:43 linux-6.6.y 60a9e718726f e2beed91 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in kvm_arch_vcpu_ioctl_run
2025/09/13 04:51 linux-6.6.y 60a9e718726f e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in kvm_arch_vcpu_ioctl_run
* Struck through repros no longer work on HEAD.