uvm_fault(0xffffffff839ff588, 0xffff8000272f2008, 0, 1) -> d
kernel: page fault trap, code=0
Stopped at      ffs2_balloc+0xa0a:      movq    0(%rcx,%rax,8),%r14
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*373567  87688      0           0  0x4000001    0  syz-executor
ffs2_balloc(fffff4006db7e400,349f1,50,fffff40007ffd680,1,ffff8000338bd538) at ffs2_balloc+0xa0a sys/ufs/ffs/ffs_balloc.c:614
ffs_write(ffff8000338bd5c0) at ffs_write+0x4f9 sys/ufs/ffs/ffs_vnops.c:345
VOP_WRITE(fffff40065bfedd0,ffff8000338bd670,3,fffff40007ffd680) at VOP_WRITE+0x101 sys/kern/vfs_vops.c:245
ktrwriteraw(ffff800035cda2c0,fffff40065bfedd0,fffff40007ffd680,ffff8000338bd740,ffff8000338bd720) at ktrwriteraw+0x19b sys/kern/kern_ktrace.c:692
ktrsysret(ffff800035cda2c0,36,0,ffff8000338bd800) at ktrsysret+0x17f ktrwrite2 sys/kern/kern_ktrace.c:-1 [inline]
ktrsysret(ffff800035cda2c0,36,0,ffff8000338bd800) at ktrsysret+0x17f sys/kern/kern_ktrace.c:209
syscall(ffff8000338bd8b0) at syscall+0xad9 mi_syscall_return sys/sys/syscall_mi.h:204 [inline]
syscall(ffff8000338bd8b0) at syscall+0xad9 sys/arch/amd64/amd64/trap.c:804
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x618593598f0, count: 8
https://www.openbsd.org/ddb.html describes the minimum info required in bug
reports.  Insufficient info makes it difficult to find and fix bugs.
ddb> 
ddb> set $lines = 0
ddb> set $maxwidth = 0
ddb> show panic
*cpu0: uvm_fault(0xffffffff839ff588, 0xffff8000272f2008, 0, 1) -> d
ddb> show kasan
No such command
ddb> trace
ffs2_balloc(fffff4006db7e400,349f1,50,fffff40007ffd680,1,ffff8000338bd538) at ffs2_balloc+0xa0a sys/ufs/ffs/ffs_balloc.c:614
ffs_write(ffff8000338bd5c0) at ffs_write+0x4f9 sys/ufs/ffs/ffs_vnops.c:345
VOP_WRITE(fffff40065bfedd0,ffff8000338bd670,3,fffff40007ffd680) at VOP_WRITE+0x101 sys/kern/vfs_vops.c:245
ktrwriteraw(ffff800035cda2c0,fffff40065bfedd0,fffff40007ffd680,ffff8000338bd740,ffff8000338bd720) at ktrwriteraw+0x19b sys/kern/kern_ktrace.c:692
ktrsysret(ffff800035cda2c0,36,0,ffff8000338bd800) at ktrsysret+0x17f ktrwrite2 sys/kern/kern_ktrace.c:-1 [inline]
ktrsysret(ffff800035cda2c0,36,0,ffff8000338bd800) at ktrsysret+0x17f sys/kern/kern_ktrace.c:209
syscall(ffff8000338bd8b0) at syscall+0xad9 mi_syscall_return sys/sys/syscall_mi.h:204 [inline]
syscall(ffff8000338bd8b0) at syscall+0xad9 sys/arch/amd64/amd64/trap.c:804
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x618593598f0, count: -7
ddb> show registers
rdi                                0
rsi                                0
rbp               0xffff8000338bd4e0
rbx               0xfffff4006db7e400
rdx               0xffff8000015ecd00
rcx               0xffff8000272f2000
rax                              0x1
r8                0xffffffffffffffff
r9                0xffff8000338bd538
r10               0x93a21bbdd4ab2b98
r11               0xcec60e9466dab6d3
r12                              0x1
r13               0xffff800000c48800
r14               0xffff8000338bd380
r15               0xfffff40060210118
rip               0xffffffff8294e52a    ffs2_balloc+0xa0a
cs                               0x8
rflags                       0x10246    __ALIGN_SIZE+0xf246
rsp               0xffff8000338bd370
ss                              0x10
ffs2_balloc+0xa0a:      movq    0(%rcx,%rax,8),%r14
ddb> show proc
PROC (syz-executor) tid=373567 pid=87688 tcnt=2 stat=onproc
    flags process=0 proc=4000001<INKTR,THREAD>
    runpri=32, usrpri=86, slppri=32, nice=20
    wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0
    forw=0xffffffffffffffff, list=0xffff800035cdafb8,0xffffffff839fe518
    process=0xffff800045ff9f98 user=0xffff8000338b8000, vmspace=0xfffff4007f22ea10
    estcpu=36, cpticks=1, pctcpu=0.0, user=0, sys=1, intr=0
ddb>