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
 160931  40209      0           0          0    0  syz-executor
*471149  21318      0           0  0x4000000    1K syz-executor
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff8344b298) at panic+0x1e5 sys/kern/subr_prf.c:198
__assert(ffffffff8348dc9d,ffffffff8349b329,17b,ffffffff834a55f6) at __assert+0x29 sys/kern/subr_prf.c:-1
bpfopen(11700,8001,2000,ffff80002a2434d0) at bpfopen+0x2bd bpfilter_lookup sys/net/bpf.c:1832 [inline]
bpfopen(11700,8001,2000,ffff80002a2434d0) at bpfopen+0x2bd sys/net/bpf.c:379
spec_open_clone(ffff80002a23ff08) at spec_open_clone+0x277 sys/kern/spec_vnops.c:722
spec_open(ffff80002a23ff08) at spec_open+0x319 sys/kern/spec_vnops.c:148
VOP_OPEN(fffffd805c806570,8001,fffffd80097fd618,ffff80002a2434d0) at VOP_OPEN+0x8b sys/kern/vfs_vops.c:138
vn_open(ffff80002a240148,8001,0) at vn_open+0x6a0 sys/kern/vfs_vnops.c:177
doopenat(ffff80002a2434d0,ffffff9c,200000000000,8000,0,0,fd1c0d5350daca82) at doopenat+0x35b sys/kern/vfs_syscalls.c:1155
sys_open(ffff80002a2434d0,ffff80002a240400,ffff80002a240350) at sys_open+0x59 sys/kern/vfs_syscalls.c:1063
syscall(ffff80002a240400) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80002a240400) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x9b801ae1250, 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(ffffffff8344b298) at panic+0x1e5 sys/kern/subr_prf.c:198
__assert(ffffffff8348dc9d,ffffffff8349b329,17b,ffffffff834a55f6) at __assert+0x29 sys/kern/subr_prf.c:-1
bpfopen(11700,8001,2000,ffff80002a2434d0) at bpfopen+0x2bd bpfilter_lookup sys/net/bpf.c:1832 [inline]
bpfopen(11700,8001,2000,ffff80002a2434d0) at bpfopen+0x2bd sys/net/bpf.c:379
spec_open_clone(ffff80002a23ff08) at spec_open_clone+0x277 sys/kern/spec_vnops.c:722
spec_open(ffff80002a23ff08) at spec_open+0x319 sys/kern/spec_vnops.c:148
VOP_OPEN(fffffd805c806570,8001,fffffd80097fd618,ffff80002a2434d0) at VOP_OPEN+0x8b sys/kern/vfs_vops.c:138
vn_open(ffff80002a240148,8001,0) at vn_open+0x6a0 sys/kern/vfs_vnops.c:177
doopenat(ffff80002a2434d0,ffffff9c,200000000000,8000,0,0,fd1c0d5350daca82) at doopenat+0x35b sys/kern/vfs_syscalls.c:1155
sys_open(ffff80002a2434d0,ffff80002a240400,ffff80002a240350) at sys_open+0x59 sys/kern/vfs_syscalls.c:1063
syscall(ffff80002a240400) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80002a240400) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x9b801ae1250, count: -12
ddb{1}> show registers
rdi                                0
rsi                              0x1
rbp               0xffff80002a23fce0
rbx               0xffff8000299bee07
rdx               0xffff8000015f4600
rcx               0xffff80002a2434d0
rax               0xffff8000299bdff0
r8                 0x101010101010101
r9                0x8080808080808080
r10               0x172f8952dfb39439
r11                 0xa9450735771272
r12               0xffff8000299bec08
r13                                0
r14                                0
r15                              0x1
rip               0xffffffff83044655    db_enter+0x25
cs                               0x8
rflags                         0x246
rsp               0xffff80002a23fcd0
ss                              0x10
db_enter+0x25:  addq    $0x8,%rsp
ddb{1}> show proc
PROC (syz-executor) tid=471149 pid=21318 tcnt=2 stat=onproc
    flags process=0 proc=4000000<THREAD>
    runpri=82, usrpri=82, slppri=32, nice=20
    wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0
    forw=0xffffffffffffffff, list=0xffff80003c3ff4e8,0xffff80002a243ca8
    process=0xffff80002a39ce88 user=0xffff80002a23b000, vmspace=0xfffffd806c8a55d0
    estcpu=32, cpticks=3, pctcpu=0.0, user=0, sys=3, intr=0
ddb{1}>