panic: kernel diagnostic assertion "len >= 0 && !M_READONLY(m)" failed: file "/syzkaller/managers/main/kernel/sys/kern/uipc_mbuf.c", line 1384
Stopped at      db_enter+0x18:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*137395   4149      0           0  0x4000000    0  syz-executor.3
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:440
panic(ffffffff8254e79b) at panic+0x161 sys/kern/subr_prf.c:202
__assert(ffffffff825bffff,ffffffff825d4d25,568,ffffffff825659c6) at __assert+0x25 sys/kern/subr_prf.c:161
m_align(fffffd80757ce200,ffffffce) at m_align+0x1a0 sys/kern/uipc_mbuf.c:1385
bpf_movein(ffff80002e863358,ffff800000c72800,ffff80002e8630b8,ffff80002e862fb8) at bpf_movein+0x25e sys/net/bpf.c:228
bpfwrite(21700,ffff80002e863358,11) at bpfwrite+0x128 sys/net/bpf.c:648
spec_write(ffff80002e8631b0) at spec_write+0xcb sys/kern/spec_vnops.c:309
VOP_WRITE(fffffd806022a398,ffff80002e863358,11,fffffd807f7d8660) at VOP_WRITE+0xbf sys/kern/vfs_vops.c:245
vn_write(fffffd806bf27b50,ffff80002e863358,0) at vn_write+0x152 sys/kern/vfs_vnops.c:414
dofilewritev(ffff8000299abce8,3,ffff80002e863358,0,ffff80002e863450) at dofilewritev+0x19c sys/kern/sys_generic.c:381
sys_write(ffff8000299abce8,ffff80002e8633f8,ffff80002e863450) at sys_write+0x83 sys/kern/sys_generic.c:301
syscall(ffff80002e8634c0) at syscall+0x44e sys/arch/amd64/amd64/trap.c:585
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xea737906d30, count: 2
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