KASAN: null-ptr-deref Read in kvm_arch_vm_ioctl

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 7ae77150 Merge tag 'powerpc-5.8-1' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1331fd05100000
kernel config: https://syzkaller.appspot.com/x/.config?x=be4578b3f1083656
dashboard link: https://syzkaller.appspot.com/bug?extid=c7721d33579672622370
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
CC: [b...@alien8.de h...@zytor.com jmat...@google.com jo...@8bytes.org k...@vger.kernel.org linux-...@vger.kernel.org mi...@redhat.com pbon...@redhat.com sean.j.chr...@intel.com tg...@linutronix.de vkuz...@redhat.com wanp...@tencent.com x...@kernel.org]

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+c7721d...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: null-ptr-deref in kvm_vm_ioctl_set_irqchip arch/x86/kvm/x86.c:4794 [inline]
BUG: KASAN: null-ptr-deref in kvm_arch_vm_ioctl+0x8bd/0x14a0 arch/x86/kvm/x86.c:5128
Read of size 8 at addr 0000000000000000 by task syz-executor.1/10765

CPU: 0 PID: 10765 Comm: syz-executor.1 Not tainted 5.7.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1e9/0x30e lib/dump_stack.c:118
__kasan_report mm/kasan/report.c:517 [inline]
kasan_report+0x151/0x1d0 mm/kasan/report.c:530
kvm_vm_ioctl_set_irqchip arch/x86/kvm/x86.c:4794 [inline]
kvm_arch_vm_ioctl+0x8bd/0x14a0 arch/x86/kvm/x86.c:5128
</IRQ>
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 10765 Comm: syz-executor.1 Tainted: G B 5.7.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1e9/0x30e lib/dump_stack.c:118
panic+0x264/0x7a0 kernel/panic.c:221
end_report mm/kasan/report.c:104 [inline]
__kasan_report mm/kasan/report.c:520 [inline]
kasan_report+0x1c9/0x1d0 mm/kasan/report.c:530
kvm_vm_ioctl_set_irqchip arch/x86/kvm/x86.c:4794 [inline]
kvm_arch_vm_ioctl+0x8bd/0x14a0 arch/x86/kvm/x86.c:5128
</IRQ>
Shutting down cpus with NMI
Kernel Offset: disabled
Rebooting in 86400 seconds..


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.