panic: kernel diagnostic assertion "bpfilter_lookup(unit) == NULL" failed: file "/syzkaller/managers/multicore/kernel/sys/net/bpf.c", line 379
Stopped at      db_enter+0x25:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
  38752  45571      0           0          0    0  syz-executor
*229812  56230      0           0  0x4000000    1K syz-executor
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff83450f17) at panic+0x1e5 sys/kern/subr_prf.c:198
__assert(ffffffff8348b8e2,ffffffff83496a31,17b,ffffffff834a01ed) at __assert+0x29 sys/kern/subr_prf.c:-1
bpfopen(11700,11,2000,ffff80002a2422a8) at bpfopen+0x2bd bpfilter_lookup sys/net/bpf.c:1832 [inline]
bpfopen(11700,11,2000,ffff80002a2422a8) at bpfopen+0x2bd sys/net/bpf.c:379
spec_open_clone(ffff80002a295e38) at spec_open_clone+0x277 sys/kern/spec_vnops.c:722
spec_open(ffff80002a295e38) at spec_open+0x319 sys/kern/spec_vnops.c:148
VOP_OPEN(fffffd806ed6b398,11,fffffd80097fd548,ffff80002a2422a8) at VOP_OPEN+0x8b sys/kern/vfs_vops.c:138
vn_open(ffff80002a296078,11,0) at vn_open+0x6a0 sys/kern/vfs_vnops.c:177
doopenat(ffff80002a2422a8,ffffff9c,200000000440,10,0,0,e312c10cfa68f4d3) at doopenat+0x35b sys/kern/vfs_syscalls.c:1155
sys_openat(ffff80002a2422a8,ffff80002a296330,ffff80002a296280) at sys_openat+0x58 sys/kern/vfs_syscalls.c:1094
syscall(ffff80002a296330) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80002a296330) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x2c13ca6f920, count: 3
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{1}> 
ddb{1}> set $lines = 0
ddb{1}> set $maxwidth = 0
ddb{1}> show panic
*cpu1: kernel diagnostic assertion "bpfilter_lookup(unit) == NULL" failed: file "/syzkaller/managers/multicore/kernel/sys/net/bpf.c", line 379
ddb{1}> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff83450f17) at panic+0x1e5 sys/kern/subr_prf.c:198
__assert(ffffffff8348b8e2,ffffffff83496a31,17b,ffffffff834a01ed) at __assert+0x29 sys/kern/subr_prf.c:-1
bpfopen(11700,11,2000,ffff80002a2422a8) at bpfopen+0x2bd bpfilter_lookup sys/net/bpf.c:1832 [inline]
bpfopen(11700,11,2000,ffff80002a2422a8) at bpfopen+0x2bd sys/net/bpf.c:379
spec_open_clone(ffff80002a295e38) at spec_open_clone+0x277 sys/kern/spec_vnops.c:722
spec_open(ffff80002a295e38) at spec_open+0x319 sys/kern/spec_vnops.c:148
VOP_OPEN(fffffd806ed6b398,11,fffffd80097fd548,ffff80002a2422a8) at VOP_OPEN+0x8b sys/kern/vfs_vops.c:138
vn_open(ffff80002a296078,11,0) at vn_open+0x6a0 sys/kern/vfs_vnops.c:177
doopenat(ffff80002a2422a8,ffffff9c,200000000440,10,0,0,e312c10cfa68f4d3) at doopenat+0x35b sys/kern/vfs_syscalls.c:1155
sys_openat(ffff80002a2422a8,ffff80002a296330,ffff80002a296280) at sys_openat+0x58 sys/kern/vfs_syscalls.c:1094
syscall(ffff80002a296330) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80002a296330) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x2c13ca6f920, count: -12
ddb{1}> show registers
rdi                                0
rsi                              0x1
rbp               0xffff80002a295c10
rbx               0xffff8000299bee07
rdx               0xffff80000007fc40
rcx               0xffff80002a2422a8
rax               0xffff8000299bdff0
r8                 0x101010101010101
r9                0x8080808080808080
r10               0x460aa9162126379e
r11               0x832a6b9c9656503d
r12               0xffff80