INIT: Entering runlevel: 2 [[36minfo[39;49m] Using makefile-style concurrent boot in runlevel 2. [....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added 'ci-upstream-kasan-gce-2,10.128.0.9' (ECDSA) to the list of known hosts. net.ipv6.conf.syz0.accept_dad = 0 net.ipv6.conf.syz0.router_solicitations = 0 executing program syzkaller login: [ 39.804384] ================================================================== [ 39.805500] BUG: KASAN: use-after-free in detach_if_pending+0x557/0x610 [ 39.806403] Write of size 8 at addr ffff8801cf193740 by task syzkaller067398/2981 [ 39.807421] [ 39.807658] CPU: 1 PID: 2981 Comm: syzkaller067398 Not tainted 4.13.0+ #77 [ 39.808597] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 39.809819] Call Trace: [ 39.810200] dump_stack+0x194/0x257 [ 39.810707] ? arch_local_irq_restore+0x53/0x53 [ 39.811334] ? show_regs_print_info+0x65/0x65 [ 39.811939] ? lock_timer_base+0x1a3/0x2b0 [ 39.812557] ? detach_if_pending+0x557/0x610 [ 39.813169] print_address_description+0x73/0x250 [ 39.813840] ? detach_if_pending+0x557/0x610 [ 39.814443] kasan_report+0x24e/0x340 [ 39.814962] __asan_report_store8_noabort+0x17/0x20 [ 39.815647] detach_if_pending+0x557/0x610 [ 39.816282] ? trace_raw_output_tick_stop+0x130/0x130 [ 39.816976] ? _raw_spin_lock_irqsave+0x9e/0xc0 [ 39.817602] ? lock_timer_base+0x1a3/0x2b0 [ 39.818201] ? lock_timer_base+0x1eb/0x2b0 [ 39.818776] ? __internal_add_timer+0x2d0/0x2d0 [ 39.819404] ? trace_hardirqs_on+0xd/0x10 [ 39.820002] try_to_del_timer_sync+0xa2/0x120 [ 39.820622] ? del_timer+0x130/0x130 [ 39.821126] ? del_timer_sync+0xeb/0x240 [ 39.821694] del_timer_sync+0x18a/0x240 [ 39.822234] tun_free_netdev+0x105/0x1b0 [ 39.822823] ? tun_xdp+0x410/0x410 [ 39.823322] ? cpumask_next+0x24/0x30 [ 39.823838] ? netdev_refcnt_read+0xed/0x150 [ 39.824433] ? tun_xdp+0x410/0x410 [ 39.824914] netdev_run_todo+0x870/0xca0 [ 39.828951] ? do_group_exit+0x149/0x400 [ 39.832988] ? register_netdev+0x30/0x30 [ 39.837024] ? lock_downgrade+0x990/0x990 [ 39.841145] ? trace_hardirqs_on+0xd/0x10 [ 39.845285] ? refcount_sub_and_test+0x115/0x1b0 [ 39.850013] ? refcount_inc+0x50/0x50 [ 39.853785] ? refcount_inc+0x50/0x50 [ 39.857561] ? sk_destruct+0x4c/0x80 [ 39.861244] ? __sk_free+0x5c/0x230 [ 39.864844] ? sk_free+0x2f/0x40 [ 39.868182] ? __tun_detach+0x176/0x1390 [ 39.872223] ? tun_attach+0xf90/0xf90 [ 39.875996] ? do_raw_spin_trylock+0x190/0x190 [ 39.880552] ? locks_remove_file+0x3fa/0x5a0 [ 39.884934] ? fcntl_setlk+0x10d0/0x10d0 [ 39.888973] ? __fsnotify_parent+0xb4/0x3a0 [ 39.893265] ? fsnotify+0x1af0/0x1af0 [ 39.897040] ? __tun_detach+0x1390/0x1390 [ 39.901162] ? __tun_detach+0x1390/0x1390 [ 39.905290] rtnl_unlock+0xe/0x10 [ 39.908711] tun_chr_close+0x49/0x60 [ 39.912401] __fput+0x333/0x7f0 [ 39.915664] ? fput+0x140/0x140 [ 39.918916] ? check_same_owner+0x320/0x320 [ 39.923209] ? _raw_spin_unlock_irq+0x27/0x70 [ 39.927678] ____fput+0x15/0x20 [ 39.930935] task_work_run+0x199/0x270 [ 39.934808] ? task_work_cancel+0x210/0x210 [ 39.939126] ? _raw_spin_unlock+0x22/0x30 [ 39.943245] ? switch_task_namespaces+0x87/0xc0 [ 39.947888] do_exit+0xa52/0x1b40 [ 39.951312] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 39.956302] ? check_noncircular+0x20/0x20 [ 39.960516] ? mm_update_next_owner+0x930/0x930 [ 39.965157] ? __pmd_alloc+0x4e0/0x4e0 [ 39.969026] ? find_held_lock+0x39/0x1d0 [ 39.973068] ? lock_downgrade+0x990/0x990 [ 39.977208] ? handle_mm_fault+0x410/0x8d0 [ 39.981420] ? down_read_trylock+0xdb/0x170 [ 39.985712] ? __handle_mm_fault+0x39c0/0x39c0 [ 39.990268] ? vmacache_find+0x61/0x270 [ 39.994225] ? up_read+0x1a/0x40 [ 39.997564] ? __do_page_fault+0x35b/0xb60 [ 40.001767] ? do_vfs_ioctl+0x492/0x1530 [ 40.005806] ? do_page_fault+0xee/0x720 [ 40.009759] ? __do_page_fault+0xb60/0xb60 [ 40.013972] ? putname+0xf3/0x130 [ 40.017402] do_group_exit+0x149/0x400 [ 40.021267] ? lockdep_sys_exit+0x47/0xf0 [ 40.025386] ? SyS_exit+0x30/0x30 [ 40.028812] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 40.033801] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 40.038530] SyS_exit_group+0x1d/0x20 [ 40.042302] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 40.047025] RIP: 0033:0x443a28 [ 40.050186] RSP: 002b:00007fff0e02d428 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 40.057865] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000443a28 [ 40.065189] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 40.072429] RBP: 0000000000000082 R08: 00000000000000e7 R09: ffffffffffffffd4 [ 40.079669] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 40.086915] R13: 00000000006d6180 R14: 0000000000000000 R15: 0000000000000000 [ 40.094171] [ 40.095768] Allocated by task 2981: [ 40.099368] save_stack_trace+0x16/0x20 [ 40.103311] save_stack+0x43/0xd0 [ 40.106733] kasan_kmalloc+0xad/0xe0 [ 40.110415] __kmalloc_node+0x47/0x70 [ 40.114185] kvmalloc_node+0x64/0xd0 [ 40.117869] alloc_netdev_mqs+0x16e/0xed0 [ 40.121984] __tun_chr_ioctl+0x12be/0x3d20 [ 40.126185] tun_chr_ioctl+0x2a/0x40 [ 40.129866] do_vfs_ioctl+0x1b1/0x1530 [ 40.133718] SyS_ioctl+0x8f/0xc0 [ 40.137057] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 40.141777] [ 40.143372] Freed by task 2981: [ 40.146619] save_stack_trace+0x16/0x20 [ 40.150561] save_stack+0x43/0xd0 [ 40.153980] kasan_slab_free+0x71/0xc0 [ 40.157833] kfree+0xca/0x250 [ 40.160905] kvfree+0x36/0x60 [ 40.163978] free_netdev+0x2cf/0x360 [ 40.167657] __tun_chr_ioctl+0x2cf6/0x3d20 [ 40.171867] tun_chr_ioctl+0x2a/0x40 [ 40.175550] do_vfs_ioctl+0x1b1/0x1530 [ 40.179405] SyS_ioctl+0x8f/0xc0 [ 40.182748] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 40.187469] [ 40.189066] The buggy address belongs to the object at ffff8801cf190340 [ 40.189066] which belongs to the cache kmalloc-16384 of size 16384 [ 40.202047] The buggy address is located 13312 bytes inside of [ 40.202047] 16384-byte region [ffff8801cf190340, ffff8801cf194340) [ 40.214494] The buggy address belongs to the page: [ 40.219392] page:ffffea00073c6400 count:1 mapcount:0 mapping:ffff8801cf190340 index:0x0 compound_mapcount: 0 [ 40.229339] flags: 0x200000000008100(slab|head) [ 40.233978] raw: 0200000000008100 ffff8801cf190340 0000000000000000 0000000100000001 [ 40.241826] raw: ffffea0007392620 ffff8801dac01c50 ffff8801dac02200 0000000000000000 [ 40.249670] page dumped because: kasan: bad access detected [ 40.255349] [ 40.256943] Memory state around the buggy address: [ 40.261840] ffff8801cf193600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 40.269170] ffff8801cf193680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 40.276496] >ffff8801cf193700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 40.283821] ^ [ 40.289237] ffff8801cf193780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 40.296565] ffff8801cf193800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 40.303897] ================================================================== [ 40.311220] Disabling lock debugging due to kernel taint [ 40.316631] Kernel panic - not syncing: panic_on_warn set ... [ 40.316631] [ 40.323956] CPU: 1 PID: 2981 Comm: syzkaller067398 Tainted: G B 4.13.0+ #77 [ 40.332147] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 40.341463] Call Trace: [ 40.344017] dump_stack+0x194/0x257 [ 40.347617] ? arch_local_irq_restore+0x53/0x53 [ 40.352249] ? vprintk_default+0x28/0x30 [ 40.356277] ? detach_if_pending+0x470/0x610 [ 40.360648] panic+0x1e4/0x417 [ 40.363805] ? __warn+0x1d9/0x1d9 [ 40.367229] ? detach_if_pending+0x557/0x610 [ 40.371600] kasan_end_report+0x50/0x50 [ 40.375542] kasan_report+0x137/0x340 [ 40.379307] __asan_report_store8_noabort+0x17/0x20 [ 40.384290] detach_if_pending+0x557/0x610 [ 40.388487] ? trace_raw_output_tick_stop+0x130/0x130 [ 40.393642] ? _raw_spin_lock_irqsave+0x9e/0xc0 [ 40.398271] ? lock_timer_base+0x1a3/0x2b0 [ 40.402469] ? lock_timer_base+0x1eb/0x2b0 [ 40.406683] ? __internal_add_timer+0x2d0/0x2d0 [ 40.411318] ? trace_hardirqs_on+0xd/0x10 [ 40.415431] try_to_del_timer_sync+0xa2/0x120 [ 40.419891] ? del_timer+0x130/0x130 [ 40.423569] ? del_timer_sync+0xeb/0x240 [ 40.427596] del_timer_sync+0x18a/0x240 [ 40.431540] tun_free_netdev+0x105/0x1b0 [ 40.435576] ? tun_xdp+0x410/0x410 [ 40.439085] ? cpumask_next+0x24/0x30 [ 40.442852] ? netdev_refcnt_read+0xed/0x150 [ 40.447228] ? tun_xdp+0x410/0x410 [ 40.450730] netdev_run_todo+0x870/0xca0 [ 40.454756] ? do_group_exit+0x149/0x400 [ 40.458782] ? register_netdev+0x30/0x30 [ 40.462807] ? lock_downgrade+0x990/0x990 [ 40.466918] ? trace_hardirqs_on+0xd/0x10 [ 40.471036] ? refcount_sub_and_test+0x115/0x1b0 [ 40.475753] ? refcount_inc+0x50/0x50 [ 40.479514] ? refcount_inc+0x50/0x50 [ 40.483281] ? sk_destruct+0x4c/0x80 [ 40.486957] ? __sk_free+0x5c/0x230 [ 40.490546] ? sk_free+0x2f/0x40 [ 40.493875] ? __tun_detach+0x176/0x1390 [ 40.497903] ? tun_attach+0xf90/0xf90 [ 40.501667] ? do_raw_spin_trylock+0x190/0x190 [ 40.506218] ? locks_remove_file+0x3fa/0x5a0 [ 40.510592] ? fcntl_setlk+0x10d0/0x10d0 [ 40.514617] ? __fsnotify_parent+0xb4/0x3a0 [ 40.518902] ? fsnotify+0x1af0/0x1af0 [ 40.522666] ? __tun_detach+0x1390/0x1390 [ 40.526776] ? __tun_detach+0x1390/0x1390 [ 40.530902] rtnl_unlock+0xe/0x10 [ 40.534318] tun_chr_close+0x49/0x60 [ 40.537995] __fput+0x333/0x7f0 [ 40.541239] ? fput+0x140/0x140 [ 40.544483] ? check_same_owner+0x320/0x320 [ 40.548768] ? _raw_spin_unlock_irq+0x27/0x70 [ 40.553230] ____fput+0x15/0x20 [ 40.556473] task_work_run+0x199/0x270 [ 40.560333] ? task_work_cancel+0x210/0x210 [ 40.564618] ? _raw_spin_unlock+0x22/0x30 [ 40.568729] ? switch_task_namespaces+0x87/0xc0 [ 40.573363] do_exit+0xa52/0x1b40 [ 40.576779] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 40.581761] ? check_noncircular+0x20/0x20 [ 40.585964] ? mm_update_next_owner+0x930/0x930 [ 40.590596] ? __pmd_alloc+0x4e0/0x4e0 [ 40.594452] ? find_held_lock+0x39/0x1d0 [ 40.598485] ? lock_downgrade+0x990/0x990 [ 40.602607] ? handle_mm_fault+0x410/0x8d0 [ 40.606803] ? down_read_trylock+0xdb/0x170 [ 40.611091] ? __handle_mm_fault+0x39c0/0x39c0 [ 40.615634] ? vmacache_find+0x61/0x270 [ 40.619577] ? up_read+0x1a/0x40 [ 40.622906] ? __do_page_fault+0x35b/0xb60 [ 40.627116] ? do_vfs_ioctl+0x492/0x1530 [ 40.631160] ? do_page_fault+0xee/0x720 [ 40.635106] ? __do_page_fault+0xb60/0xb60 [ 40.639304] ? putname+0xf3/0x130 [ 40.642726] do_group_exit+0x149/0x400 [ 40.646587] ? lockdep_sys_exit+0x47/0xf0 [ 40.650697] ? SyS_exit+0x30/0x30 [ 40.654115] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 40.659096] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 40.663817] SyS_exit_group+0x1d/0x20 [ 40.667582] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 40.672303] RIP: 0033:0x443a28 [ 40.675468] RSP: 002b:00007fff0e02d428 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 40.683143] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000443a28 [ 40.690386] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 40.697619] RBP: 0000000000000082 R08: 00000000000000e7 R09: ffffffffffffffd4 [ 40.704854] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 40.712090] R13: 00000000006d6180 R14: 0000000000000000 R15: 0000000000000000