[v5.15] WARNING in kvm_apic_accept_events

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 1c700860e8bc Linux 5.15.185
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11802c0c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=db74c56dea20051
dashboard link: https://syzkaller.appspot.com/bug?extid=3fca9e42187b60fc6ede
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/98c9bcd8fb21/disk-1c700860.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/75eaa3b1c3f3/vmlinux-1c700860.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ed251e9d15fe/bzImage-1c700860.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3fca9e...@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 1 PID: 7360 at arch/x86/kvm/lapic.c:2932 kvm_apic_accept_events+0x435/0x550 arch/x86/kvm/lapic.c:2932
Modules linked in:
CPU: 1 PID: 7360 Comm: syz.1.768 Not tainted 5.15.185-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:kvm_apic_accept_events+0x435/0x550 arch/x86/kvm/lapic.c:2932
Code: 00 00 00 65 48 8b 04 25 28 00 00 00 48 3b 44 24 60 75 1e 44 89 e0 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 fb a9 61 00 <0f> 0b e9 9d fd ff ff e8 7f 54 8b 08 89 d9 80 e1 07 80 c1 03 38 c1
RSP: 0018:ffffc900030cfb60 EFLAGS: 00010283
RAX: ffffffff81161825 RBX: 0000000000000002 RCX: 0000000000080000
RDX: ffffc900057b1000 RSI: 0000000000000418 RDI: 0000000000000419
RBP: ffffc900030cfc20 R08: dffffc0000000000 R09: fffffbfff1ff3652
R10: fffffbfff1ff3652 R11: 1ffffffff1ff3651 R12: ffffc900030cfba0
R13: dffffc0000000000 R14: ffff888050c80304 R15: ffff888029fbdce8
FS: 00007f5c186076c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7c278582d8 CR3: 000000005c8ed000 CR4: 00000000003526f0
Call Trace:
<TASK>
vcpu_block arch/x86/kvm/x86.c:10116 [inline]
vcpu_run arch/x86/kvm/x86.c:10164 [inline]
kvm_arch_vcpu_ioctl_run+0xd46/0x1f40 arch/x86/kvm/x86.c:10399
kvm_vcpu_ioctl+0x887/0xb80 virt/kvm/kvm_main.c:3894
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f5c1a79f929
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:00007f5c18607038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f5c1a9c6fa0 RCX: 00007f5c1a79f929
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 00007f5c1a821b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f5c1a9c6fa0 R15: 00007fffe3f40e98
</TASK>


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 1c700860e8bc Linux 5.15.185
git tree: linux-5.15.y

console output: https://syzkaller.appspot.com/x/log.txt?x=1240b1d4580000

kernel config: https://syzkaller.appspot.com/x/.config?x=db74c56dea20051
dashboard link: https://syzkaller.appspot.com/bug?extid=3fca9e42187b60fc6ede
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12c60c0c580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16c60c0c580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/98c9bcd8fb21/disk-1c700860.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/75eaa3b1c3f3/vmlinux-1c700860.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ed251e9d15fe/bzImage-1c700860.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3fca9e...@syzkaller.appspotmail.com

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: 1 PID: 4165 at arch/x86/kvm/lapic.c:2932 kvm_apic_accept_events+0x435/0x550 arch/x86/kvm/lapic.c:2932
Modules linked in:
CPU: 1 PID: 4165 Comm: syz-executor323 Not tainted 5.15.185-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:kvm_apic_accept_events+0x435/0x550 arch/x86/kvm/lapic.c:2932
Code: 00 00 00 65 48 8b 04 25 28 00 00 00 48 3b 44 24 60 75 1e 44 89 e0 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 fb a9 61 00 <0f> 0b e9 9d fd ff ff e8 7f 54 8b 08 89 d9 80 e1 07 80 c1 03 38 c1

RSP: 0018:ffffc90002eafb60 EFLAGS: 00010293
RAX: ffffffff81161825 RBX: 0000000000000002 RCX: ffff88807f6f9dc0
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000002
RBP: ffffc90002eafc20 R08: dffffc0000000000 R09: fffffbfff1ff3633
R10: fffffbfff1ff3633 R11: 1ffffffff1ff3632 R12: ffffc90002eafba0
R13: dffffc0000000000 R14: ffff88807d2d8304 R15: ffff8880786540e8
FS: 000055556b002380(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000200000002000 CR3: 000000006e076000 CR4: 00000000003526e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Call Trace:
<TASK>
vcpu_block arch/x86/kvm/x86.c:10116 [inline]
vcpu_run arch/x86/kvm/x86.c:10164 [inline]
kvm_arch_vcpu_ioctl_run+0xd46/0x1f40 arch/x86/kvm/x86.c:10399
kvm_vcpu_ioctl+0x887/0xb80 virt/kvm/kvm_main.c:3894
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0

RIP: 0033:0x7f8b47cb4bf9
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd7adef038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007f8b47cb4bf9

RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005

RBP: 0000200000bfe000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd7adef040
R13: 0000200000bff000 R14: 0000000000000004 R15: 0000000000000001
</TASK>


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