executing program syzkaller login: [ 21.839143] refcount_t: underflow; use-after-free. [ 21.839523] ------------[ cut here ]------------ [ 21.839850] WARNING: CPU: 1 PID: 3010 at lib/refcount.c:186 refcount_sub_and_test+0x167/0x1b0 [ 21.840437] Kernel panic - not syncing: panic_on_warn set ... [ 21.840437] [ 21.840922] CPU: 1 PID: 3010 Comm: syzkaller675191 Not tainted 4.13.0-rc5-next-20170817+ #5 [ 21.841464] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 [ 21.841989] Call Trace: [ 21.842206] dump_stack+0x194/0x257 [ 21.842439] ? arch_local_irq_restore+0x53/0x53 [ 21.842740] panic+0x1e4/0x417 [ 21.842943] ? __warn+0x1d9/0x1d9 [ 21.843165] ? show_regs_print_info+0x65/0x65 [ 21.843457] ? refcount_sub_and_test+0x167/0x1b0 [ 21.843761] __warn+0x1c4/0x1d9 [ 21.843971] ? refcount_sub_and_test+0x167/0x1b0 [ 21.844274] report_bug+0x211/0x2d0 [ 21.844508] fixup_bug+0x40/0x90 [ 21.844724] do_trap+0x260/0x390 [ 21.844945] do_error_trap+0x120/0x390 [ 21.845194] ? do_trap+0x390/0x390 [ 21.845419] ? refcount_sub_and_test+0x167/0x1b0 [ 21.845749] ? vprintk_emit+0x3ea/0x590 [ 21.846007] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 21.846339] do_invalid_op+0x1b/0x20 [ 21.846576] invalid_op+0x18/0x20 [ 21.846797] RIP: 0010:refcount_sub_and_test+0x167/0x1b0 [ 21.847135] RSP: 0018:ffff88006a276320 EFLAGS: 00010286 [ 21.847474] RAX: 0000000000000026 RBX: 0000000000000001 RCX: 0000000000000000 [ 21.847988] RDX: 0000000000000026 RSI: 1ffff1000d44ec24 RDI: ffffed000d44ec58 [ 21.848488] RBP: ffff88006a2763b0 R08: 0000000000000000 R09: 1ffff1000d44ebf6 [ 21.849006] R10: ffff88006a276150 R11: ffffffff85b2cbf8 R12: 1ffff1000d44ec65 [ 21.849587] R13: 00000000ffffff01 R14: 0000000000000100 R15: ffff88006cc179bc [ 21.850194] ? refcount_inc+0x50/0x50 [ 21.850494] ? __sctp_outq_teardown+0xc7d/0x15a0 [ 21.850812] ? sctp_association_free+0x2d0/0x930 [ 21.851129] ? sctp_do_sm+0x28e7/0x6d90 [ 21.851469] ? sctp_primitive_SHUTDOWN+0xa0/0xd0 [ 21.851913] ? sctp_close+0x3c6/0x980 [ 21.852292] ? inet_release+0xed/0x1c0 [ 21.852677] ? sock_release+0x8d/0x1e0 [ 21.853063] ? sock_close+0x16/0x20 [ 21.853382] sctp_wfree+0x183/0x620 [ 21.853743] ? exit_to_usermode_loop+0x224/0x300 [ 21.854140] ? syscall_return_slowpath+0x42f/0x500 [ 21.854453] ? __sctp_write_space+0x910/0x910 [ 21.854741] skb_release_head_state+0x124/0x200 [ 21.855037] skb_release_all+0x15/0x60 [ 21.855286] consume_skb+0x153/0x490 [ 21.855523] ? sctp_chunk_put+0x99/0x420 [ 21.855810] ? alloc_skb_with_frags+0x710/0x710 [ 21.856109] ? sctp_chunk_hold+0x20/0x20 [ 21.856369] ? lock_acquire+0x1d5/0x580 [ 21.856622] ? lock_acquire+0x1d5/0x580 [ 21.856878] ? refcount_sub_and_test+0x115/0x1b0 [ 21.857182] ? refcount_inc+0x50/0x50 [ 21.857426] ? trace_hardirqs_off+0xd/0x10 [ 21.857924] ? quarantine_put+0xeb/0x190 [ 21.858238] sctp_chunk_put+0x29c/0x420 [ 21.858608] ? sctp_chunk_hold+0x20/0x20 [ 21.858960] ? sctp_transport_dst_confirm+0x50/0x50 [ 21.859390] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 21.859838] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 21.860282] ? lock_downgrade+0x990/0x990 [ 21.860642] sctp_chunk_free+0x53/0x60 [ 21.861038] __sctp_outq_teardown+0xc7d/0x15a0 [ 21.861343] ? sctp_inq_set_th_handler+0x1b0/0x1b0 [ 21.861732] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 21.862242] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 21.862726] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 21.863095] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 21.863486] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 21.863824] ? fsnotify_recalc_mask.part.6+0xa0/0xa0 [ 21.864217] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 21.864560] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 21.864943] ? lock_acquire+0x1d5/0x580 [ 21.865202] ? lock_acquire+0x1d5/0x580 [ 21.865488] ? lock_timer_base+0x1a3/0x2b0 [ 21.865794] ? lock_acquire+0x1d5/0x580 [ 21.866106] ? lock_acquire+0x1d5/0x580 [ 21.866502] ? sock_def_wakeup+0x1f9/0x350 [ 21.866894] ? lock_downgrade+0x990/0x990 [ 21.867194] ? lock_release+0xa40/0xa40 [ 21.867454] ? __next_timer_interrupt+0x150/0x150 [ 21.867823] sctp_outq_free+0x15/0x20 [ 21.868073] sctp_association_free+0x2d0/0x930 [ 21.868423] ? refcount_inc+0x50/0x50 [ 21.868751] ? sctp_asconf_queue_teardown+0x700/0x700 [ 21.869120] ? sock_def_wakeup+0x222/0x350 [ 21.869474] ? sk_dst_check+0x560/0x560 [ 21.869789] ? sctp_association_put+0x74/0x2f0 [ 21.870166] ? sctp_association_hold+0x20/0x20 [ 21.870517] ? lock_acquire+0x1d5/0x580 [ 21.870802] ? is_bpf_text_address+0x7b/0x120 [ 21.871119] ? sctp_sm_lookup_event+0x95/0x3c0 [ 21.871430] sctp_do_sm+0x28e7/0x6d90 [ 21.871771] ? lock_acquire+0x1d5/0x580 [ 21.872083] ? depot_save_stack+0x3b5/0x490 [ 21.872395] ? sctp_do_8_2_transport_strike.isra.16+0x8a0/0x8a0 [ 21.872874] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 21.873234] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 21.873570] ? depot_save_stack+0x3b5/0x490 [ 21.873933] ? rcu_segcblist_first_pend_cb+0x90/0x90 [ 21.874295] ? trace_hardirqs_on+0xd/0x10 [ 21.874592] ? lock_acquire+0x1d5/0x580 [ 21.874954] ? skb_dequeue+0x12a/0x180 [ 21.875208] ? lock_downgrade+0x990/0x990 [ 21.875505] ? do_raw_spin_trylock+0x190/0x190 [ 21.875887] ? lock_release+0xa40/0xa40 [ 21.876190] ? trace_hardirqs_on+0xd/0x10 [ 21.876529] sctp_primitive_SHUTDOWN+0xa0/0xd0 [ 21.876949] sctp_close+0x3c6/0x980 [ 21.877247] ? sctp_apply_peer_addr_params+0xf30/0xf30 [ 21.877642] ? trace_hardirqs_on+0xd/0x10 [ 21.877980] ? rcu_eqs_enter_common.constprop.73+0x270/0x270 [ 21.878395] ? fsnotify_grab_connector+0x14e/0x270 [ 21.878741] ? node_tag_set+0xae/0x130 [ 21.879325] ? locks_remove_file+0x3fa/0x5a0 [ 21.879611] ? fcntl_setlk+0x10c0/0x10c0 [ 21.879872] ? radix_tree_iter_tag_set+0x97/0xd0 [ 21.880179] ? __fsnotify_parent+0xb4/0x3a0 [ 21.880487] ? ip_mc_drop_socket+0x1ce/0x230 [ 21.880915] inet_release+0xed/0x1c0 [ 21.881260] sock_release+0x8d/0x1e0 [ 21.881592] ? sock_release+0x1e0/0x1e0 [ 21.881883] sock_close+0x16/0x20 [ 21.882137] __fput+0x327/0x7e0 [ 21.882355] ? fput+0x140/0x140 [ 21.882598] ? check_same_owner+0x320/0x320 [ 21.882905] ____fput+0x15/0x20 [ 21.883120] task_work_run+0x199/0x270 [ 21.883373] ? task_work_cancel+0x210/0x210 [ 21.883680] ? free_nsproxy+0x185/0x1f0 [ 21.883938] ? switch_task_namespaces+0xa2/0xc0 [ 21.884244] do_exit+0xa52/0x1b30 [ 21.884500] ? __sched_text_start+0x8/0x8 [ 21.884796] ? lock_release+0xa40/0xa40 [ 21.885061] ? mm_update_next_owner+0x930/0x930 [ 21.885364] ? sctp_outq_uncork+0x5a/0x70 [ 21.885634] ? sctp_do_sm+0x49b/0x6d90 [ 21.885919] ? sctp_do_8_2_transport_strike.isra.16+0x8a0/0x8a0 [ 21.886308] ? lock_acquire+0x1d5/0x580 [ 21.886594] ? finish_wait+0x268/0x490 [ 21.886865] ? lock_downgrade+0x990/0x990 [ 21.887149] ? do_raw_spin_trylock+0x190/0x190 [ 21.887478] ? trace_hardirqs_on+0xd/0x10 [ 21.887773] ? refcount_sub_and_test+0x115/0x1b0 [ 21.888111] ? release_sock+0x1d4/0x2a0 [ 21.888371] ? lock_downgrade+0x990/0x990 [ 21.888642] ? lock_downgrade+0x990/0x990 [ 21.888928] ? __dequeue_signal+0x103/0x7b0 [ 21.889249] ? recalc_sigpending_tsk+0x117/0x150 [ 21.889567] ? get_signal+0x855/0x17e0 [ 21.889829] ? lock_downgrade+0x990/0x990 [ 21.890108] ? __local_bh_enable_ip+0x9d/0x160 [ 21.890402] do_group_exit+0x149/0x400 [ 21.890652] ? SyS_exit+0x30/0x30 [ 21.890874] ? sctp_primitive_SEND+0xa0/0xd0 [ 21.891164] get_signal+0x7e8/0x17e0 [ 21.891412] ? ptrace_notify+0x130/0x130 [ 21.891674] ? release_sock+0x1d4/0x2a0 [ 21.891956] ? trace_hardirqs_on+0xd/0x10 [ 21.892221] ? __local_bh_enable_ip+0x9d/0x160 [ 21.892513] ? _raw_spin_unlock_bh+0x30/0x40 [ 21.892795] ? release_sock+0x1d4/0x2a0 [ 21.893053] ? __release_sock+0x360/0x360 [ 21.893323] ? trace_hardirqs_on+0xd/0x10 [ 21.893590] do_signal+0x94/0x1ee0 [ 21.893819] ? inet_sendmsg+0x11f/0x5e0 [ 21.894075] ? inet_sendmsg+0x126/0x5e0 [ 21.894331] ? __might_sleep+0x95/0x190 [ 21.894588] ? setup_sigcontext+0x7d0/0x7d0 [ 21.894866] ? selinux_socket_sendmsg+0x36/0x40 [ 21.895167] ? security_socket_sendmsg+0x89/0xb0 [ 21.895472] ? inet_recvmsg+0x5f0/0x5f0 [ 21.895728] ? sock_sendmsg+0x4f/0x110 [ 21.895979] ? fput+0xd2/0x140 [ 21.896186] ? SYSC_sendto+0x40d/0x5a0 [ 21.896436] ? SYSC_connect+0x470/0x470 [ 21.896720] ? up_read+0x1a/0x40 [ 21.896942] ? __do_page_fault+0x35b/0xb60 [ 21.897217] exit_to_usermode_loop+0x224/0x300 [ 21.897512] ? trace_event_raw_event_sys_exit+0x260/0x260 [ 21.897872] syscall_return_slowpath+0x42f/0x500 [ 21.898185] ? finish_task_switch+0x1aa/0x740 [ 21.898475] ? prepare_exit_to_usermode+0x2c0/0x2c0 [ 21.898798] ? prepare_exit_to_usermode+0x1a0/0x2c0 [ 21.899121] ? perf_trace_sys_enter+0xc20/0xc20 [ 21.899423] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 21.899732] entry_SYSCALL_64_fastpath+0xbc/0xbe [ 21.900093] RIP: 0033:0x43b2a9 [ 21.900561] RSP: 002b:00007f432d855db8 EFLAGS: 00000206 ORIG_RAX: 000000000000002c [ 21.901063] RAX: 000000000000009b RBX: 0000000000000000 RCX: 000000000043b2a9 [ 21.901525] RDX: 000000000000009b RSI: 0000000020381000 RDI: 0000000000000003 [ 21.901985] RBP: 0000000000000000 R08: 0000000020a63ff0 R09: 0000000000000010 [ 21.902446] R10: 0000000000004000 R11: 0000000000000206 R12: 0000000000000000 [ 21.902908] R13: 0000000000000000 R14: 00007f432d8569c0 R15: 00007f432d856700 [ 21.903410] Dumping ftrace buffer: [ 21.903644] (ftrace buffer empty) [ 21.903885] Kernel Offset: disabled [ 21.904123] Rebooting in 86400 seconds..