IPVS: ftp: loaded support on port[0] = 21
Zero length message leads to an empty skb
ODEBUG: free active (active state 0) object type: rcu_head hint:           (null)
------------[ cut here ]------------
WARNING: CPU: 0 PID: 0 at lib/debugobjects.c:287 debug_print_object.cold+0xa7/0xdb lib/debugobjects.c:287
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.14.273-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 panic+0x1f9/0x42d kernel/panic.c:183
 __warn.cold+0x20/0x44 kernel/panic.c:547
 report_bug+0x208/0x250 lib/bug.c:183
 fixup_bug arch/x86/kernel/traps.c:177 [inline]
 fixup_bug arch/x86/kernel/traps.c:172 [inline]
 do_error_trap+0x195/0x2d0 arch/x86/kernel/traps.c:295
 invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:964
RIP: 0010:debug_print_object.cold+0xa7/0xdb lib/debugobjects.c:287
RSP: 0018:ffff8880ba407d00 EFLAGS: 00010082
RAX: 0000000000000051 RBX: 0000000000000003 RCX: 0000000000000000
RDX: 0000000000000100 RSI: ffffffff878bc340 RDI: ffffed1017480f96
RBP: ffffffff878b14c0 R08: 0000000000000051 R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff88e74440 R12: 0000000000000000
R13: 0000000000000000 R14: ffff88809d6c5c00 R15: ffff8880a99c7f50
 __debug_check_no_obj_freed lib/debugobjects.c:747 [inline]
 debug_check_no_obj_freed+0x3b7/0x680 lib/debugobjects.c:776
 kfree+0xb9/0x250 mm/slab.c:3814
 __tcindex_destroy+0x2e/0x70 net/sched/cls_tcindex.c:253
 __rcu_reclaim kernel/rcu/rcu.h:195 [inline]
 rcu_do_batch kernel/rcu/tree.c:2699 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2962 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2929 [inline]
 rcu_process_callbacks+0x780/0x1180 kernel/rcu/tree.c:2946
 __do_softirq+0x24d/0x9ff kernel/softirq.c:288
 invoke_softirq kernel/softirq.c:368 [inline]
 irq_exit+0x193/0x240 kernel/softirq.c:409
 exiting_irq arch/x86/include/asm/apic.h:638 [inline]
 smp_apic_timer_interrupt+0x141/0x5e0 arch/x86/kernel/apic/apic.c:1106
 apic_timer_interrupt+0x93/0xa0 arch/x86/entry/entry_64.S:793
 </IRQ>
RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61
RSP: 0018:ffffffff88e07e78 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff10
RAX: 1ffffffff11e12f4 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000001 RDI: ffffffff88e74cc4
RBP: ffffffff88f09790 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: fffffbfff11ce888
R13: ffffffff88e74440 R14: 0000000000000000 R15: 0000000000000000
 arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline]
 default_idle+0x47/0x370 arch/x86/kernel/process.c:558
 cpuidle_idle_call kernel/sched/idle.c:156 [inline]
 do_idle+0x250/0x3c0 kernel/sched/idle.c:246
 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:351
 start_kernel+0x750/0x770 init/main.c:708
 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240

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