panic: init died (signal NUM, exit NUM)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c8ac761eb131 virtio: Fix condition for buffer chaining, ne..
git tree: openbsd
console output: https://syzkaller.appspot.com/x/log.txt?x=17368f1a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1bc15e68cd2a49e5
dashboard link: https://syzkaller.appspot.com/bug?extid=a200d8b9daa7da40c566

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/54d55d488989/disk-c8ac761e.raw.xz
bsd.gdb: https://storage.googleapis.com/syzbot-assets/735cc5a6f0c9/bsd-c8ac761e.gdb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/97c8a13f273a/kernel-c8ac761e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a200d8...@syzkaller.appspotmail.com

panic: init died (signal 0, exit 11)
Starting stack trace...
panic(ffffffff8338adc5) at panic+0x1ba sys/kern/subr_prf.c:229
exit1(ffff80002a72dc88,b,0,1) at exit1+0x127 sys/kern/kern_exit.c:135
sys_exit(ffff80002a72dc88,ffff80002a72b960,ffff80002a72b8b0) at sys_exit+0x1a sys/kern/kern_exit.c:-1
syscall(ffff80002a72b960) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80002a72b960) at syscall+0x962 sys/arch/amd64/amd64/trap.c:775
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x7eb29b37e780, count: 252
End of stack trace.
syncing disks...46 42 done

dump to dev 4,1 not possible
rebooting...
SeaBIOS (version 1.8.2-google)
Total RAM Size = 0x0000000080000000 = 2048 MiB
CPUs found: 2 Max CPUs supported: 2
SeaBIOS (version 1.8.2-google)
Machine UUID 9c8ab089-5fb3-144b-a4ba-2e178800b25c
found virtio-scsi at 0:3
virtio-scsi vendor='Google' product='PersistentDisk' rev='1' type=0 removable=0
virtio-scsi blksize=512 sectors=4194304 = 2048 MiB
drive 0x000f26e0: PCHS=0/0/0 translation=lba LCHS=520/128/63 s=4194304
Sending Seabios boot VM event.
Booting from Hard Disk 0...
>> OpenBSD/amd64 BOOT 3.67
boot> set $lines = 0
set: syntax error
boot> set $maxwidth = 0
set: syntax error
boot> show panic
boot: illegal argument panic
boot> trace
boot> show registers
boot> show proc
boot> ps
boot> show all locks
boot> show malloc
boot> show all pools
boot> machine ddbcpu 0
machine: syntax error
boot> trace
boot> machine ddbcpu 1
machine: syntax error
boot> trace


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