executing program executing program syzkaller login: [ 35.932146] refcount_t: underflow; use-after-free. [ 35.932885] ------------[ cut here ]------------ [ 35.933728] WARNING: CPU: 2 PID: 3055 at lib/refcount.c:186 refcount_sub_and_test+0x167/0x1b0 [ 35.934677] Kernel panic - not syncing: panic_on_warn set ... [ 35.934677] [ 35.935334] CPU: 2 PID: 3055 Comm: syzkaller889760 Not tainted 4.13.0-rc6-next-20170828+ #10 [ 35.936063] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 [ 35.936761] Call Trace: [ 35.936949] dump_stack+0x194/0x257 [ 35.937218] ? arch_local_irq_restore+0x53/0x53 [ 35.937566] panic+0x1e4/0x41c [ 35.937789] ? refcount_error_report+0x214/0x214 [ 35.938127] ? show_regs_print_info+0x65/0x65 [ 35.938553] ? refcount_sub_and_test+0x167/0x1b0 [ 35.939038] __warn+0x1c4/0x1e0 [ 35.939378] ? refcount_sub_and_test+0x167/0x1b0 [ 35.939868] report_bug+0x211/0x2d0 [ 35.940271] fixup_bug+0x40/0x90 [ 35.940625] do_trap+0x260/0x390 [ 35.940987] do_error_trap+0x120/0x390 [ 35.941407] ? do_trap+0x390/0x390 [ 35.941775] ? refcount_sub_and_test+0x167/0x1b0 [ 35.942264] ? vprintk_emit+0x3ea/0x590 [ 35.942681] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 35.943115] do_invalid_op+0x1b/0x20 [ 35.943370] invalid_op+0x18/0x20 [ 35.943622] RIP: 0010:refcount_sub_and_test+0x167/0x1b0 [ 35.944271] RSP: 0018:ffff88006ab0e320 EFLAGS: 00010286 [ 35.944676] RAX: 0000000000000026 RBX: 0000000000000001 RCX: 0000000000000000 [ 35.945378] RDX: 0000000000000026 RSI: 1ffff1000d561c24 RDI: ffffed000d561c58 [ 35.945888] RBP: ffff88006ab0e3b0 R08: ffff88006ab0da10 R09: 0000000000000000 [ 35.946390] R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1000d561c65 [ 35.946920] R13: 00000000ffffff01 R14: 0000000000000100 R15: ffff88003a542a24 [ 35.947523] ? refcount_inc+0x50/0x50 [ 35.947876] ? __sctp_outq_teardown+0xc7d/0x15a0 [ 35.948263] ? sctp_association_free+0x2d0/0x930 [ 35.948622] ? sctp_do_sm+0x28e7/0x6dd0 [ 35.948895] ? sctp_primitive_SHUTDOWN+0xa0/0xd0 [ 35.949296] ? sctp_close+0x3c6/0x980 [ 35.949659] ? inet_release+0xed/0x1c0 [ 35.949928] sctp_wfree+0x183/0x620 [ 35.950167] ? __sctp_write_space+0x910/0x910 [ 35.950464] skb_release_head_state+0x124/0x200 [ 35.950991] skb_release_all+0x15/0x60 [ 35.951399] consume_skb+0x153/0x490 [ 35.951776] ? sctp_chunk_put+0x99/0x420 [ 35.952217] ? alloc_skb_with_frags+0x710/0x710 [ 35.952780] ? sctp_chunk_hold+0x20/0x20 [ 35.953197] ? refcount_sub_and_test+0x115/0x1b0 [ 35.953662] ? refcount_inc+0x50/0x50 [ 35.954003] ? mark_held_locks+0xb2/0x100 [ 35.954381] ? sctp_datamsg_put+0x456/0x560 [ 35.954775] sctp_chunk_put+0x29c/0x420 [ 35.955136] ? sctp_chunk_hold+0x20/0x20 [ 35.955430] ? sctp_transport_dst_confirm+0x50/0x50 [ 35.955790] ? debug_check_no_locks_freed+0x3d0/0x3d0 [ 35.956263] sctp_chunk_free+0x53/0x60 [ 35.956616] __sctp_outq_teardown+0xc7d/0x15a0 [ 35.957029] ? sock_release+0x8d/0x1e0 [ 35.957387] ? sctp_inq_set_th_handler+0x1b0/0x1b0 [ 35.957747] ? unwind_next_frame.part.6+0x1ae/0xc70 [ 35.958195] ? unwind_next_frame.part.6+0x1ae/0xc70 [ 35.958648] ? unwind_dump+0x4c0/0x4c0 [ 35.958999] ? unwind_next_frame.part.6+0x1ae/0xc70 [ 35.959467] ? unwind_dump+0x4c0/0x4c0 [ 35.959829] ? check_noncircular+0x20/0x20 [ 35.960182] ? check_noncircular+0x20/0x20 [ 35.960565] ? unwind_get_return_address+0x61/0xa0 [ 35.961010] ? __save_stack_trace+0x61/0xd0 [ 35.961401] ? check_noncircular+0x20/0x20 [ 35.961786] ? print_usage_bug+0x480/0x480 [ 35.962177] ? find_held_lock+0x39/0x1d0 [ 35.962555] ? lock_downgrade+0x990/0x990 [ 35.962937] ? sk_dst_check+0x560/0x560 [ 35.963223] ? rcu_read_lock_sched_held+0x108/0x120 [ 35.963671] ? lock_release+0xd70/0xd70 [ 35.964029] sctp_outq_free+0x15/0x20 [ 35.964369] sctp_association_free+0x2d0/0x930 [ 35.964775] ? sctp_asconf_queue_teardown+0x700/0x700 [ 35.965608] ? sock_def_wakeup+0x222/0x350 [ 35.966042] ? sk_dst_check+0x560/0x560 [ 35.966429] ? sctp_association_put+0x74/0x2f0 [ 35.966836] ? sctp_association_hold+0x20/0x20 [ 35.967267] ? sctp_sm_lookup_event+0x95/0x3c0 [ 35.967699] sctp_do_sm+0x28e7/0x6dd0 [ 35.968071] ? sctp_do_8_2_transport_strike.isra.16+0x8a0/0x8a0 [ 35.968600] ? save_stack_trace+0x16/0x20 [ 35.968967] ? print_usage_bug+0x480/0x480 [ 35.969339] ? get_signal+0x7e8/0x17e0 [ 35.969686] ? print_usage_bug+0x480/0x480 [ 35.970062] ? find_held_lock+0x39/0x1d0 [ 35.970429] ? lock_downgrade+0x990/0x990 [ 35.970799] ? skb_dequeue+0x22/0x180 [ 35.971157] ? do_raw_spin_trylock+0x190/0x190 [ 35.971567] ? mark_held_locks+0xb2/0x100 [ 35.971942] ? trace_hardirqs_on+0xd/0x10 [ 35.972315] sctp_primitive_SHUTDOWN+0xa0/0xd0 [ 35.972762] sctp_close+0x3c6/0x980 [ 35.973104] ? sctp_apply_peer_addr_params+0xf30/0xf30 [ 35.973534] ? check_noncircular+0x20/0x20 [ 35.973906] ? _raw_spin_unlock_irqrestore+0xa6/0xba [ 35.974355] ? depot_save_stack+0x3b5/0x490 [ 35.974739] ? locks_remove_file+0x3fa/0x5a0 [ 35.975128] ? fcntl_setlk+0x10d0/0x10d0 [ 35.975552] ? __fsnotify_parent+0xb4/0x3a0 [ 35.975958] ? ip_mc_drop_socket+0x1ce/0x230 [ 35.976296] inet_release+0xed/0x1c0 [ 35.976610] sock_release+0x8d/0x1e0 [ 35.976936] ? sock_release+0x1e0/0x1e0 [ 35.977279] sock_close+0x16/0x20 [ 35.977587] __fput+0x333/0x7f0 [ 35.977880] ? fput+0x140/0x140 [ 35.978170] ? _raw_spin_unlock_irq+0x27/0x70 [ 35.978568] ____fput+0x15/0x20 [ 35.978858] task_work_run+0x199/0x270 [ 35.979210] ? task_work_cancel+0x210/0x210 [ 35.979589] ? _raw_spin_unlock+0x22/0x30 [ 35.979952] ? switch_task_namespaces+0x87/0xc0 [ 35.980365] do_exit+0xa52/0x1b40 [ 35.980684] ? mm_update_next_owner+0x930/0x930 [ 35.981097] ? __is_insn_slot_addr+0x1fc/0x330 [ 35.981500] ? lock_downgrade+0x990/0x990 [ 35.981876] ? __read_once_size_nocheck.constprop.8+0x10/0x10 [ 35.982393] ? is_bpf_text_address+0x7b/0x120 [ 35.982791] ? lock_downgrade+0x990/0x990 [ 35.983168] ? show_initstate+0xb0/0xb0 [ 35.983548] ? check_noncircular+0x20/0x20 [ 35.983921] ? bpf_prog_alloc+0x310/0x310 [ 35.984294] ? lock_release+0xd70/0xd70 [ 35.984647] ? __free_insn_slot+0x5c0/0x5c0 [ 35.985028] ? unwind_dump+0x4c0/0x4c0 [ 35.985373] ? find_held_lock+0x39/0x1d0 [ 35.985741] ? lock_downgrade+0x990/0x990 [ 35.986537] ? recalc_sigpending_tsk+0x117/0x150 [ 35.986868] ? recalc_sigpending+0x103/0x160 [ 35.987192] ? recalc_sigpending_tsk+0x150/0x150 [ 35.987641] ? get_signal+0x397/0x17e0 [ 35.988011] do_group_exit+0x149/0x400 [ 35.988374] ? __lock_is_held+0xbc/0x140 [ 35.988736] ? SyS_exit+0x30/0x30 [ 35.989044] ? _raw_spin_unlock_irq+0x27/0x70 [ 35.989463] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 35.989915] get_signal+0x7e8/0x17e0 [ 35.990271] ? ptrace_notify+0x130/0x130 [ 35.990655] ? check_noncircular+0x20/0x20 [ 35.991041] do_signal+0x94/0x1ee0 [ 35.991373] ? setup_sigcontext+0x7d0/0x7d0 [ 35.991758] ? find_held_lock+0x39/0x1d0 [ 35.992129] ? rcu_pm_notify+0xc0/0xc0 [ 35.992477] ? lock_acquire+0x1d5/0x580 [ 35.992828] ? exit_to_usermode_loop+0x98/0x300 [ 35.993244] exit_to_usermode_loop+0x224/0x300 [ 35.993650] ? trace_event_raw_event_sys_exit+0x260/0x260 [ 35.994136] ? _raw_spin_unlock_irq+0x27/0x70 [ 35.994535] syscall_return_slowpath+0x42f/0x500 [ 35.994948] ? finish_task_switch+0x1aa/0x740 [ 35.995351] ? prepare_exit_to_usermode+0x2c0/0x2c0 [ 35.995698] ? preempt_notifier_dec+0x20/0x20 [ 35.996102] ret_from_fork+0x15/0x40 [ 35.996358] RIP: 0033:0x43eb49 [ 35.996635] RSP: 002b:00007f814fb22e70 EFLAGS: 00000202 ORIG_RAX: 0000000000000038 [ 35.997279] RAX: 0000000000000000 RBX: 00007f814fb23700 RCX: 000000000043eb49 [ 35.997907] RDX: 00007f814fb239d0 RSI: 00007f814fb22e70 RDI: 00000000003d0f00 [ 35.998538] RBP: 00000000007efd70 R08: 00007f814fb23700 R09: 00007f814fb23700 [ 35.999033] R10: 00007f814fb239d0 R11: 0000000000000202 R12: 0000000000000000 [ 35.999668] R13: 0000000000000000 R14: 00007f814fb239c0 R15: 00007f814fb23700 [ 36.000445] Dumping ftrace buffer: [ 36.000756] (ftrace buffer empty) [ 36.001026] Kernel Offset: disabled [ 36.001297] Rebooting in 86400 seconds..