login: panic: mtx_lock() of spin mutex (null) @ /syzkaller/managers/i386/kernel/sys/kern/uipc_sockbuf.c:360
cpuid = 1
time = 1569555071
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x47/frame 0xfffffe0019eeffd0
vpanic() at vpanic+0x1e0/frame 0xfffffe0019ef0030
panic() at panic+0x43/frame 0xfffffe0019ef0090
__mtx_lock_flags() at __mtx_lock_flags+0x1fd/frame 0xfffffe0019ef00f0
socantrcvmore() at socantrcvmore+0x2c/frame 0xfffffe0019ef0110
sctp_notify_assoc_change() at sctp_notify_assoc_change+0x5c9/frame 0xfffffe0019ef0190
sctp_process_control() at sctp_process_control+0x86b1/frame 0xfffffe0019ef0610
sctp_common_input_processing() at sctp_common_input_processing+0x755/frame 0xfffffe0019ef07a0
sctp_input_with_port() at sctp_input_with_port+0x30e/frame 0xfffffe0019ef0890
sctp_input() at sctp_input+0x1f/frame 0xfffffe0019ef08b0
ip_input() at ip_input+0x2c4/frame 0xfffffe0019ef0970
swi_net() at swi_net+0x23b/frame 0xfffffe0019ef09f0
ithread_loop() at ithread_loop+0x2f2/frame 0xfffffe0019ef0a60
fork_exit() at fork_exit+0xb0/frame 0xfffffe0019ef0ab0
fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe0019ef0ab0
--- trap 0, rip = 0, rsp = 0, rbp = 0 ---
KDB: enter: panic
[ thread pid 12 tid 100017 ]
Stopped at      kdb_enter+0x6a: movq    $0,kdb_why