panic: kernel diagnostic assertion "ifp != NULL" failed: file "/syzkaller/managers/multicore/kernel/sys/netinet/if_ether.c", line 759
Stopped at      db_enter+0x1c:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*385758  52455      0     0x14000      0x200    0  softclockmp
db_enter() at db_enter+0x1c sys/arch/amd64/amd64/db_interface.c:437
panic(ffffffff827a8426) at panic+0x17b sys/kern/subr_prf.c:198
__assert(ffffffff82826a8a,ffffffff82820123,2f7,ffffffff827732c8) at __assert+0x29 sys/kern/subr_prf.c:157
arptfree(fffffd80652104d8) at arptfree+0x132 sys/netinet/if_ether.c:759
arptimer(ffffffff82cb2f28) at arptimer+0x88 sys/netinet/if_ether.c:135
timeout_run(ffffffff82cb2f28) at timeout_run+0xd0 sys/kern/kern_timeout.c:665
softclock_thread_mp(ffff800021159298) at softclock_thread_mp+0xc4 sys/kern/kern_timeout.c:833
end trace frame: 0x0, count: 8
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