------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: lib/refcount.c:25 at refcount_warn_saturate+0x9f/0x110, CPU#1: swapper/1/0
Modules linked in:
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:refcount_warn_saturate+0x9f/0x110
Code: eb 66 85 db 74 3e 83 fb 01 75 4c e8 0b 33 14 fd 48 8d 3d 74 b4 8c 0b 67 48 0f b9 3a eb 4a e8 f8 32 14 fd 48 8d 3d 71 b4 8c 0b <67> 48 0f b9 3a eb 37 e8 e5 32 14 fd 48 8d 3d 6e b4 8c 0b 67 48 0f
RSP: 0018:ffffc90000a08c28 EFLAGS: 00010246
RAX: ffffffff84b18c78 RBX: 0000000000000002 RCX: ffff888160470000
RDX: 0000000000000100 RSI: ffffffff8f10e040 RDI: ffffffff903e40f0
RBP: 0000000000000000 R08: ffff888160470000 R09: 0000000000000005
R10: 0000000000000004 R11: 0000000000000100 R12: dffffc0000000000
R13: 0000000000000001 R14: ffff8881a4506004 R15: ffff8881a45063c0
FS:  0000000000000000(0000) GS:ffff8882a921b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000102fde000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 sctp_generate_timeout_event+0x1c8/0x390
 call_timer_fn+0x192/0x5e0
 __run_timer_base+0x652/0x8b0
 run_timer_softirq+0xb7/0x170
 handle_softirqs+0x22a/0x840
 __irq_exit_rcu+0xca/0x220
 irq_exit_rcu+0x9/0x30
 sysvec_apic_timer_interrupt+0xa6/0xc0
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:pv_native_safe_halt+0xf/0x20
Code: bb 71 02 e9 53 f4 02 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa eb 07 0f 00 2d 13 a1 11 00 fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90
RSP: 0018:ffffc90000197e20 EFLAGS: 00000202
RAX: 0000000000666583 RBX: ffffffff819a9e9a RCX: 0000000080000001
RDX: 0000000000000001 RSI: ffffffff8dfd579c RDI: ffffffff8c289de0
RBP: ffffc90000197f10 R08: ffff88823c6339db R09: 1ffff110478c673b
R10: dffffc0000000000 R11: ffffed10478c673c R12: 0000000000000001
R13: 1ffff1102c08e000 R14: 0000000000000001 R15: 1ffff1102c08e000
 default_idle+0x9/0x20
 default_idle_call+0x72/0xb0
 do_idle+0x36a/0x5f0
 cpu_startup_entry+0x43/0x60
 start_secondary+0x101/0x110
 common_startup_64+0x13e/0x147
 </TASK>
