INIT: Entering runlevel: 2 [info] Using makefile-style concurrent boot in runlevel 2. [....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added 'ci-upstream-net-kasan-gce-4,10.128.0.4' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 42.523810] refcount_t: underflow; use-after-free. [ 42.524742] ------------[ cut here ]------------ [ 42.525653] WARNING: CPU: 1 PID: 3003 at lib/refcount.c:186 refcount_sub_and_test+0x167/0x1b0 [ 42.526808] Kernel panic - not syncing: panic_on_warn set ... [ 42.526808] [ 42.527811] CPU: 1 PID: 3003 Comm: syzkaller500251 Not tainted 4.13.0-rc4+ #5 [ 42.528794] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 42.530151] Call Trace: [ 42.530597] dump_stack+0x194/0x257 [ 42.531097] ? arch_local_irq_restore+0x53/0x53 [ 42.531825] panic+0x1e4/0x417 [ 42.532261] ? __warn+0x1d9/0x1d9 [ 42.532749] ? show_regs_print_info+0x65/0x65 [ 42.533363] ? refcount_sub_and_test+0x167/0x1b0 [ 42.534043] __warn+0x1c4/0x1d9 [ 42.534540] ? refcount_sub_and_test+0x167/0x1b0 [ 42.535254] report_bug+0x211/0x2d0 [ 42.535770] fixup_bug+0x40/0x90 [ 42.536260] do_trap+0x260/0x390 [ 42.536745] do_error_trap+0x120/0x390 [ 42.537298] ? vprintk_emit+0x49b/0x590 [ 42.537997] ? do_trap+0x390/0x390 [ 42.538472] ? refcount_sub_and_test+0x167/0x1b0 [ 42.539272] ? vprintk_emit+0x3ea/0x590 [ 42.539814] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 42.540498] do_invalid_op+0x1b/0x20 [ 42.541096] invalid_op+0x1e/0x30 [ 42.541558] RIP: 0010:refcount_sub_and_test+0x167/0x1b0 [ 42.542276] RSP: 0018:ffff8801d0546928 EFLAGS: 00010282 [ 42.543013] RAX: 0000000000000026 RBX: 0000000000000001 RCX: 0000000000000000 [ 42.544025] RDX: 0000000000000026 RSI: 1ffff1003a0a8ce5 RDI: ffffed003a0a8d19 [ 42.551259] RBP: ffff8801d05469b8 R08: 0000000000000001 R09: 0000000000000000 [ 42.558502] R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1003a0a8d26 [ 42.565930] R13: 00000000ffffff01 R14: 0000000000000100 R15: ffff8801cf30fa3c [ 42.573228] ? refcount_sub_and_test+0x167/0x1b0 [ 42.577963] ? refcount_inc+0x50/0x50 [ 42.581742] ? __sctp_outq_teardown+0xc7d/0x15a0 [ 42.586463] ? sctp_association_free+0x2d0/0x930 [ 42.591182] ? sctp_do_sm+0x28e7/0x6d90 [ 42.595120] ? sctp_primitive_SHUTDOWN+0xa0/0xd0 [ 42.599841] ? sctp_close+0x3c6/0x980 [ 42.603629] ? inet_release+0xed/0x1c0 [ 42.607486] sctp_wfree+0x183/0x620 [ 42.611079] ? __sctp_write_space+0x910/0x910 [ 42.615559] skb_release_head_state+0x124/0x200 [ 42.620206] skb_release_all+0x15/0x60 [ 42.624066] consume_skb+0x153/0x490 [ 42.627832] ? sctp_chunk_put+0x99/0x420 [ 42.631860] ? alloc_skb_with_frags+0x710/0x710 [ 42.636500] ? sctp_chunk_hold+0x20/0x20 [ 42.640544] ? refcount_sub_and_test+0x115/0x1b0 [ 42.645267] ? refcount_inc+0x50/0x50 [ 42.649033] ? mark_held_locks+0xaf/0x100 [ 42.653149] ? sctp_datamsg_put+0x456/0x560 [ 42.657441] sctp_chunk_put+0x29c/0x420 [ 42.661393] ? sctp_chunk_hold+0x20/0x20 [ 42.665424] ? sctp_transport_dst_confirm+0x50/0x50 [ 42.670433] sctp_chunk_free+0x53/0x60 [ 42.674286] __sctp_outq_teardown+0xc7d/0x15a0 [ 42.678833] ? bpf_prog_kallsyms_find+0xbd/0x440 [ 42.683566] ? sctp_inq_set_th_handler+0x1b0/0x1b0 [ 42.688459] ? is_bpf_text_address+0x7b/0x120 [ 42.692919] ? lock_downgrade+0x990/0x990 [ 42.697033] ? lock_release+0xa40/0xa40 [ 42.700975] ? update_stack_state+0x700/0x700 [ 42.705465] ? print_usage_bug+0x480/0x480 [ 42.709676] ? is_bpf_text_address+0xa4/0x120 [ 42.714138] ? __kernel_text_address+0xae/0xe0 [ 42.718692] ? unwind_get_return_address+0x61/0xa0 [ 42.723587] ? __save_stack_trace+0x7e/0xd0 [ 42.727876] ? check_noncircular+0x20/0x20 [ 42.732078] ? print_usage_bug+0x480/0x480 [ 42.736279] ? save_stack_trace+0x16/0x20 [ 42.740393] ? save_trace+0x11f/0x350 [ 42.744165] ? lock_acquire+0x1d5/0x580 [ 42.748112] ? lock_acquire+0x1d5/0x580 [ 42.752052] ? lock_timer_base+0x1a3/0x2b0 [ 42.756256] ? find_held_lock+0x35/0x1d0 [ 42.760292] ? sock_def_wakeup+0x1f9/0x350 [ 42.764491] ? lock_downgrade+0x990/0x990 [ 42.768623] ? lock_release+0xa40/0xa40 [ 42.772567] sctp_outq_free+0x15/0x20 [ 42.776351] sctp_association_free+0x2d0/0x930 [ 42.780911] ? sctp_asconf_queue_teardown+0x700/0x700 [ 42.786069] ? sock_def_wakeup+0x222/0x350 [ 42.790270] ? sk_dst_check+0x560/0x560 [ 42.794213] ? sctp_association_put+0x74/0x2f0 [ 42.798782] ? sctp_association_hold+0x20/0x20 [ 42.803340] ? sctp_sm_lookup_event+0x95/0x3c0 [ 42.807890] sctp_do_sm+0x28e7/0x6d90 [ 42.811659] ? check_noncircular+0x20/0x20 [ 42.815868] ? sctp_do_8_2_transport_strike.isra.16+0x8a0/0x8a0 [ 42.821894] ? print_usage_bug+0x480/0x480 [ 42.826096] ? print_usage_bug+0x480/0x480 [ 42.830310] ? find_held_lock+0x35/0x1d0 [ 42.834341] ? skb_dequeue+0x12a/0x180 [ 42.838191] ? lock_downgrade+0x990/0x990 [ 42.842309] ? do_raw_spin_trylock+0x190/0x190 [ 42.846860] ? mark_held_locks+0xaf/0x100 [ 42.850978] ? trace_hardirqs_on+0xd/0x10 [ 42.855098] sctp_primitive_SHUTDOWN+0xa0/0xd0 [ 42.859650] sctp_close+0x3c6/0x980 [ 42.863264] ? sctp_apply_peer_addr_params+0xf30/0xf30 [ 42.868506] ? unwind_get_return_address+0x61/0xa0 [ 42.873402] ? __save_stack_trace+0x7e/0xd0 [ 42.877695] ? check_noncircular+0x20/0x20 [ 42.881902] ? ipv6_sock_ac_close+0x2e8/0x3e0 [ 42.886365] ? ipv6_sock_mc_close+0x148/0x1a0 [ 42.890825] ? ipv6_sock_ac_drop+0x580/0x580 [ 42.895197] ? ip_mc_drop_socket+0x1ce/0x230 [ 42.899579] ? __fsnotify_parent+0xb4/0x3a0 [ 42.903872] inet_release+0xed/0x1c0 [ 42.907553] inet6_release+0x50/0x70 [ 42.911233] sock_release+0x8d/0x1e0 [ 42.914914] ? sock_release+0x1e0/0x1e0 [ 42.918860] sock_close+0x16/0x20 [ 42.922279] __fput+0x327/0x7e0 [ 42.925545] ? fput+0x140/0x140 [ 42.928792] ? do_raw_spin_trylock+0x190/0x190 [ 42.933354] ? check_same_owner+0x320/0x320 [ 42.937644] ____fput+0x15/0x20 [ 42.940899] task_work_run+0x18a/0x260 [ 42.944757] ? task_work_cancel+0x210/0x210 [ 42.949045] ? _raw_spin_unlock+0x22/0x30 [ 42.953158] ? switch_task_namespaces+0x87/0xc0 [ 42.957805] do_exit+0xa3a/0x1b10 [ 42.961223] ? find_held_lock+0x35/0x1d0 [ 42.965258] ? lock_downgrade+0x990/0x990 [ 42.969372] ? mm_update_next_owner+0x930/0x930 [ 42.974018] ? __lock_is_held+0xb6/0x140 [ 42.978065] ? __fd_install+0x2f7/0x6a0 [ 42.982004] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 42.986744] ? get_unused_fd_flags+0x190/0x190 [ 42.991317] ? copy_user_generic_unrolled+0x89/0xc0 [ 42.996303] ? _copy_to_user+0xa2/0xc0 [ 43.000163] ? fd_install+0x4d/0x60 [ 43.003759] ? SYSC_accept4+0x4ec/0x850 [ 43.007703] ? kernel_accept+0x2f0/0x2f0 [ 43.011731] ? lock_downgrade+0x990/0x990 [ 43.015854] ? handle_mm_fault+0x4e3/0x940 [ 43.020057] ? __handle_mm_fault+0x3810/0x3810 [ 43.024604] ? vmacache_find+0x61/0x270 [ 43.028549] do_group_exit+0x149/0x400 [ 43.032403] ? SyS_exit+0x30/0x30 [ 43.035821] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 43.040805] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 43.045548] SyS_exit_group+0x1d/0x20 [ 43.049318] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 43.054037] RIP: 0033:0x43e9f8 [ 43.057192] RSP: 002b:00007ffd25539d58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 43.064876] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043e9f8 [ 43.072111] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 43.079347] RBP: 0000000000000086 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 43.086591] R10: 000000000000001c R11: 0000000000000246 R12: 0000000000401720 [ 43.093827] R13: 00000000004017b0 R14: 0000000000000000 R15: 0000000000000000 [ 43.101223] Dumping ftrace buffer: [ 43.104771] (ftrace buffer empty) [ 43.108452] Kernel Offset: disabled [ 43.112050] Rebooting in 86400 seconds..