panic: mallocarray: overflow 18446744071562067968 * 8
Stopped at      db_enter+0x18:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
 121630  76538      0           0          0    1  syz-executor.1
* 86379  76538      0           0  0x4000000    0K syz-executor.1
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:399
panic() at panic+0x174 sys/kern/subr_prf.c:208
db_show_all_nfsreqs(ffffffff80000000,8,2,2) at db_show_all_nfsreqs
wsmux_getmux(7fffffff) at wsmux_getmux+0x71 sys/dev/wscons/wsmux.c:152
wsmux_add_mux(7fffffff,ffff800000026f00) at wsmux_add_mux+0x2f sys/dev/wscons/wsmux.c:594
VOP_IOCTL(fffffd8068976498,80085761,ffff800020c1d4a0,2,fffffd807f7c6b40,ffff800020b28270) at VOP_IOCTL+0x9a sys/kern/vfs_vops.c:290
vn_ioctl(fffffd806cb65600,80085761,ffff800020c1d4a0,ffff800020b28270) at vn_ioctl+0xc9 sys/kern/vfs_vnops.c:512
sys_ioctl(ffff800020b28270,ffff800020c1d5e8,ffff800020c1d5d0) at sys_ioctl+0x651
syscall(ffff800020c1d680) at syscall+0x5b8 mi_syscall sys/sys/syscall_mi.h:99 [inline]
syscall(ffff800020c1d680) at syscall+0x5b8 sys/arch/amd64/amd64/trap.c:574
Xsyscall(6,0,ffffffffffffff86,0,3,4faf17b4010) at Xsyscall+0x128
end of kernel
end trace frame: 0x4fd01b5a840, count: 5
https://www.openbsd.org/ddb.html describes the minimum info required in bug
reports.  Insufficient info makes it difficult to find and fix bugs.