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-next-kasan-gce-6,10.128.0.13' (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: [ 41.470740] ================================================================== [ 41.478199] BUG: KASAN: use-after-free in detach_if_pending+0x557/0x610 [ 41.484931] Write of size 8 at addr ffff8801ce9037c0 by task syzkaller054707/2981 [ 41.492541] [ 41.494152] CPU: 0 PID: 2981 Comm: syzkaller054707 Not tainted 4.13.0-next-20170905+ #15 [ 41.502358] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 41.511702] Call Trace: [ 41.514443] dump_stack+0x194/0x257 [ 41.518323] ? arch_local_irq_restore+0x53/0x53 [ 41.522971] ? show_regs_print_info+0x65/0x65 [ 41.527448] ? lock_timer_base+0x1a3/0x2b0 [ 41.531668] ? detach_if_pending+0x557/0x610 [ 41.536051] print_address_description+0x73/0x250 [ 41.541131] ? detach_if_pending+0x557/0x610 [ 41.545535] kasan_report+0x24e/0x340 [ 41.549404] __asan_report_store8_noabort+0x17/0x20 [ 41.554437] detach_if_pending+0x557/0x610 [ 41.558653] ? trace_raw_output_tick_stop+0x130/0x130 [ 41.563840] ? _raw_spin_lock_irqsave+0x9e/0xc0 [ 41.568524] ? lock_timer_base+0x1a3/0x2b0 [ 41.572763] ? lock_timer_base+0x1eb/0x2b0 [ 41.576979] ? __internal_add_timer+0x2d0/0x2d0 [ 41.581623] ? trace_hardirqs_on+0xd/0x10 [ 41.585776] try_to_del_timer_sync+0xa2/0x120 [ 41.590250] ? del_timer+0x130/0x130 [ 41.593941] ? del_timer_sync+0xeb/0x240 [ 41.598016] del_timer_sync+0x18a/0x240 [ 41.602026] tun_free_netdev+0x105/0x1b0 [ 41.606097] ? tun_xdp+0x410/0x410 [ 41.609707] ? cpumask_next+0x24/0x30 [ 41.613494] ? netdev_refcnt_read+0xed/0x150 [ 41.617967] ? tun_xdp+0x410/0x410 [ 41.621566] netdev_run_todo+0x870/0xca0 [ 41.625600] ? do_group_exit+0x149/0x400 [ 41.629987] ? register_netdev+0x30/0x30 [ 41.634025] ? lock_downgrade+0x990/0x990 [ 41.638146] ? trace_hardirqs_on+0xd/0x10 [ 41.642369] ? refcount_sub_and_test+0x115/0x1b0 [ 41.647106] ? refcount_inc+0x50/0x50 [ 41.650878] ? refcount_inc+0x50/0x50 [ 41.654665] ? sk_destruct+0x4c/0x80 [ 41.658351] ? __sk_free+0x5c/0x230 [ 41.661952] ? sk_free+0x2f/0x40 [ 41.665306] ? __tun_detach+0x176/0x1390 [ 41.669352] ? tun_attach+0xf90/0xf90 [ 41.673142] ? do_raw_spin_trylock+0x190/0x190 [ 41.678135] ? locks_remove_file+0x3fa/0x5a0 [ 41.682868] ? fcntl_setlk+0x10d0/0x10d0 [ 41.686906] ? __fsnotify_parent+0xb4/0x3a0 [ 41.691259] ? fsnotify+0x1af0/0x1af0 [ 41.695053] ? __tun_detach+0x1390/0x1390 [ 41.699189] ? __tun_detach+0x1390/0x1390 [ 41.703426] rtnl_unlock+0xe/0x10 [ 41.706851] tun_chr_close+0x49/0x60 [ 41.710536] __fput+0x333/0x7f0 [ 41.713811] ? fput+0x140/0x140 [ 41.717090] ? check_same_owner+0x320/0x320 [ 41.721385] ? _raw_spin_unlock_irq+0x27/0x70 [ 41.725858] ____fput+0x15/0x20 [ 41.729120] task_work_run+0x199/0x270 [ 41.733592] ? task_work_cancel+0x210/0x210 [ 41.737896] ? _raw_spin_unlock+0x22/0x30 [ 41.742463] ? switch_task_namespaces+0x87/0xc0 [ 41.747112] do_exit+0xa52/0x1b40 [ 41.750541] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 41.755534] ? check_noncircular+0x20/0x20 [ 41.759773] ? mm_update_next_owner+0x930/0x930 [ 41.764418] ? __pmd_alloc+0x4e0/0x4e0 [ 41.768302] ? find_held_lock+0x39/0x1d0 [ 41.772345] ? lock_downgrade+0x990/0x990 [ 41.777801] ? handle_mm_fault+0x4a2/0x860 [ 41.782019] ? down_read_trylock+0xdb/0x170 [ 41.786332] ? __handle_mm_fault+0x39c0/0x39c0 [ 41.790909] ? vmacache_find+0x61/0x270 [ 41.794870] ? up_read+0x1a/0x40 [ 41.798224] ? __do_page_fault+0x35b/0xb60 [ 41.802442] ? do_vfs_ioctl+0x492/0x1530 [ 41.806485] ? do_page_fault+0xee/0x720 [ 41.810446] ? __do_page_fault+0xb60/0xb60 [ 41.814672] ? putname+0xf3/0x130 [ 41.818105] do_group_exit+0x149/0x400 [ 41.821965] ? lockdep_sys_exit+0x47/0xf0 [ 41.826093] ? SyS_exit+0x30/0x30 [ 41.829528] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 41.834519] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 41.839251] SyS_exit_group+0x1d/0x20 [ 41.843035] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 41.847764] RIP: 0033:0x443ad8 [ 41.850925] RSP: 002b:00007fff39ada7a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 41.858607] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000443ad8 [ 41.865868] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 41.873220] RBP: 0000000000000082 R08: 00000000000000e7 R09: ffffffffffffffd4 [ 41.880471] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 41.888429] R13: 00000000006d6180 R14: 0000000000000000 R15: 0000000000000000 [ 41.895700] [ 41.897309] Allocated by task 2981: [ 41.900950] save_stack_trace+0x16/0x20 [ 41.904983] save_stack+0x43/0xd0 [ 41.908407] kasan_kmalloc+0xad/0xe0 [ 41.912099] __kmalloc_node+0x47/0x70 [ 41.915873] kvmalloc_node+0x64/0xd0 [ 41.919561] alloc_netdev_mqs+0x16e/0xed0 [ 41.923787] __tun_chr_ioctl+0x12be/0x3d20 [ 41.928010] tun_chr_ioctl+0x2a/0x40 [ 41.931714] do_vfs_ioctl+0x1b1/0x1530 [ 41.935589] SyS_ioctl+0x8f/0xc0 [ 41.938932] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 41.943655] [ 41.945256] Freed by task 2981: [ 41.948517] save_stack_trace+0x16/0x20 [ 41.952473] save_stack+0x43/0xd0 [ 41.955896] kasan_slab_free+0x71/0xc0 [ 41.959773] kfree+0xca/0x250 [ 41.962854] kvfree+0x36/0x60 [ 41.965940] free_netdev+0x2cf/0x360 [ 41.969628] __tun_chr_ioctl+0x2cf6/0x3d20 [ 41.973831] tun_chr_ioctl+0x2a/0x40 [ 41.977522] do_vfs_ioctl+0x1b1/0x1530 [ 41.981388] SyS_ioctl+0x8f/0xc0 [ 41.984728] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 41.989451] [ 41.991051] The buggy address belongs to the object at ffff8801ce9003c0 [ 41.991051] which belongs to the cache kmalloc-16384 of size 16384 [ 42.004033] The buggy address is located 13312 bytes inside of [ 42.004033] 16384-byte region [ffff8801ce9003c0, ffff8801ce9043c0) [ 42.016366] The buggy address belongs to the page: [ 42.021282] page:ffffea00073a4000 count:1 mapcount:0 mapping:ffff8801ce9003c0 index:0x0 compound_mapcount: 0 [ 42.031230] flags: 0x200000000008100(slab|head) [ 42.035871] raw: 0200000000008100 ffff8801ce9003c0 0000000000000000 0000000100000001 [ 42.043724] raw: ffffea0007336020 ffff8801dac01c50 ffff8801dac02200 0000000000000000 [ 42.051575] page dumped because: kasan: bad access detected [ 42.057254] [ 42.058851] Memory state around the buggy address: [ 42.063772] ffff8801ce903680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 42.071131] ffff8801ce903700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 42.078468] >ffff8801ce903780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 42.085816] ^ [ 42.091247] ffff8801ce903800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 42.098597] ffff8801ce903880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 42.105925] ================================================================== [ 42.113259] Disabling lock debugging due to kernel taint [ 42.118712] Kernel panic - not syncing: panic_on_warn set ... [ 42.118712] [ 42.126061] CPU: 0 PID: 2981 Comm: syzkaller054707 Tainted: G B 4.13.0-next-20170905+ #15 [ 42.135650] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 42.144974] Call Trace: [ 42.147545] dump_stack+0x194/0x257 [ 42.151144] ? arch_local_irq_restore+0x53/0x53 [ 42.155781] ? vprintk_default+0x28/0x30 [ 42.159810] ? detach_if_pending+0x530/0x610 [ 42.164188] panic+0x1e4/0x417 [ 42.167347] ? __warn+0x1d9/0x1d9 [ 42.170773] ? detach_if_pending+0x557/0x610 [ 42.175148] kasan_end_report+0x50/0x50 [ 42.179089] kasan_report+0x137/0x340 [ 42.182880] __asan_report_store8_noabort+0x17/0x20 [ 42.187881] detach_if_pending+0x557/0x610 [ 42.192105] ? trace_raw_output_tick_stop+0x130/0x130 [ 42.202315] ? _raw_spin_lock_irqsave+0x9e/0xc0 [ 42.207225] ? lock_timer_base+0x1a3/0x2b0 [ 42.211445] ? lock_timer_base+0x1eb/0x2b0 [ 42.215649] ? __internal_add_timer+0x2d0/0x2d0 [ 42.220296] ? trace_hardirqs_on+0xd/0x10 [ 42.224413] try_to_del_timer_sync+0xa2/0x120 [ 42.228878] ? del_timer+0x130/0x130 [ 42.232644] ? del_timer_sync+0xeb/0x240 [ 42.236674] del_timer_sync+0x18a/0x240 [ 42.240616] tun_free_netdev+0x105/0x1b0 [ 42.244708] ? tun_xdp+0x410/0x410 [ 42.248230] ? cpumask_next+0x24/0x30 [ 42.252012] ? netdev_refcnt_read+0xed/0x150 [ 42.256407] ? tun_xdp+0x410/0x410 [ 42.259921] netdev_run_todo+0x870/0xca0 [ 42.263951] ? do_group_exit+0x149/0x400 [ 42.268000] ? register_netdev+0x30/0x30 [ 42.272033] ? lock_downgrade+0x990/0x990 [ 42.276147] ? trace_hardirqs_on+0xd/0x10 [ 42.280273] ? refcount_sub_and_test+0x115/0x1b0 [ 42.285019] ? refcount_inc+0x50/0x50 [ 42.288796] ? refcount_inc+0x50/0x50 [ 42.292579] ? sk_destruct+0x4c/0x80 [ 42.296259] ? __sk_free+0x5c/0x230 [ 42.299871] ? sk_free+0x2f/0x40 [ 42.303208] ? __tun_detach+0x176/0x1390 [ 42.307250] ? tun_attach+0xf90/0xf90 [ 42.311032] ? do_raw_spin_trylock+0x190/0x190 [ 42.315608] ? locks_remove_file+0x3fa/0x5a0 [ 42.319991] ? fcntl_setlk+0x10d0/0x10d0 [ 42.324035] ? __fsnotify_parent+0xb4/0x3a0 [ 42.328335] ? fsnotify+0x1af0/0x1af0 [ 42.332118] ? __tun_detach+0x1390/0x1390 [ 42.336233] ? __tun_detach+0x1390/0x1390 [ 42.340360] rtnl_unlock+0xe/0x10 [ 42.343782] tun_chr_close+0x49/0x60 [ 42.347461] __fput+0x333/0x7f0 [ 42.350709] ? fput+0x140/0x140 [ 42.353966] ? check_same_owner+0x320/0x320 [ 42.358253] ? _raw_spin_unlock_irq+0x27/0x70 [ 42.362716] ____fput+0x15/0x20 [ 42.365963] task_work_run+0x199/0x270 [ 42.369817] ? task_work_cancel+0x210/0x210 [ 42.374107] ? _raw_spin_unlock+0x22/0x30 [ 42.378228] ? switch_task_namespaces+0x87/0xc0 [ 42.382885] do_exit+0xa52/0x1b40 [ 42.386314] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 42.391299] ? check_noncircular+0x20/0x20 [ 42.395504] ? mm_update_next_owner+0x930/0x930 [ 42.400140] ? __pmd_alloc+0x4e0/0x4e0 [ 42.403998] ? find_held_lock+0x39/0x1d0 [ 42.408046] ? lock_downgrade+0x990/0x990 [ 42.412171] ? handle_mm_fault+0x4a2/0x860 [ 42.416371] ? down_read_trylock+0xdb/0x170 [ 42.420668] ? __handle_mm_fault+0x39c0/0x39c0 [ 42.425230] ? vmacache_find+0x61/0x270 [ 42.429175] ? up_read+0x1a/0x40 [ 42.432528] ? __do_page_fault+0x35b/0xb60 [ 42.436734] ? do_vfs_ioctl+0x492/0x1530 [ 42.440772] ? do_page_fault+0xee/0x720 [ 42.444723] ? __do_page_fault+0xb60/0xb60 [ 42.449283] ? putname+0xf3/0x130 [ 42.452715] do_group_exit+0x149/0x400 [ 42.456782] ? lockdep_sys_exit+0x47/0xf0 [ 42.460995] ? SyS_exit+0x30/0x30 [ 42.464435] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 42.469456] ? trace_hardirqs_on_thunk+0x1a/0x1c