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-3,10.128.0.17' (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: [ 32.858327] ================================================================== [ 32.865738] BUG: KASAN: use-after-free in detach_if_pending+0x557/0x610 [ 32.872463] Write of size 8 at addr ffff8801cd4eb740 by task syzkaller755397/2986 [ 32.880048] [ 32.881649] CPU: 1 PID: 2986 Comm: syzkaller755397 Not tainted 4.13.0-next-20170915+ #23 [ 32.889844] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 32.899170] Call Trace: [ 32.901733] dump_stack+0x194/0x257 [ 32.905336] ? arch_local_irq_restore+0x53/0x53 [ 32.909979] ? show_regs_print_info+0x65/0x65 [ 32.914448] ? lock_timer_base+0x1a3/0x2b0 [ 32.918654] ? detach_if_pending+0x557/0x610 [ 32.923033] print_address_description+0x73/0x250 [ 32.927844] ? detach_if_pending+0x557/0x610 [ 32.932223] kasan_report+0x24e/0x340 [ 32.935999] __asan_report_store8_noabort+0x17/0x20 [ 32.940985] detach_if_pending+0x557/0x610 [ 32.945193] ? trace_raw_output_tick_stop+0x130/0x130 [ 32.950354] ? _raw_spin_lock_irqsave+0x9e/0xc0 [ 32.954988] ? lock_timer_base+0x1a3/0x2b0 [ 32.959191] ? lock_timer_base+0x1eb/0x2b0 [ 32.963397] ? __internal_add_timer+0x2d0/0x2d0 [ 32.968038] ? trace_hardirqs_on+0xd/0x10 [ 32.972177] try_to_del_timer_sync+0xa2/0x120 [ 32.976645] ? del_timer+0x130/0x130 [ 32.980332] ? del_timer_sync+0xeb/0x240 [ 32.984371] del_timer_sync+0x18a/0x240 [ 32.988320] tun_free_netdev+0x105/0x1b0 [ 32.992352] ? tun_xdp+0x410/0x410 [ 32.995863] ? cpumask_next+0x24/0x30 [ 32.999635] ? netdev_refcnt_read+0xed/0x150 [ 33.004016] ? tun_xdp+0x410/0x410 [ 33.007527] netdev_run_todo+0x870/0xca0 [ 33.011560] ? do_group_exit+0x149/0x400 [ 33.015596] ? register_netdev+0x30/0x30 [ 33.019632] ? lock_downgrade+0x990/0x990 [ 33.023759] ? trace_hardirqs_on+0xd/0x10 [ 33.027899] ? refcount_sub_and_test+0x115/0x1b0 [ 33.032622] ? refcount_inc+0x50/0x50 [ 33.036393] ? refcount_inc+0x50/0x50 [ 33.040167] ? sk_destruct+0x4c/0x80 [ 33.043851] ? __sk_free+0x5c/0x230 [ 33.047451] ? sk_free+0x2f/0x40 [ 33.050785] ? __tun_detach+0x176/0x1390 [ 33.054828] ? tun_attach+0xf90/0xf90 [ 33.058608] ? locks_remove_file+0x3fa/0x5a0 [ 33.062996] ? fcntl_setlk+0x10d0/0x10d0 [ 33.067028] ? __fsnotify_parent+0xb4/0x3a0 [ 33.071322] ? fsnotify+0x1af0/0x1af0 [ 33.075095] ? __tun_detach+0x1390/0x1390 [ 33.079768] ? __tun_detach+0x1390/0x1390 [ 33.083888] rtnl_unlock+0xe/0x10 [ 33.087310] tun_chr_close+0x49/0x60 [ 33.090993] __fput+0x333/0x7f0 [ 33.094247] ? fput+0x140/0x140 [ 33.097496] ? check_same_owner+0x320/0x320 [ 33.101794] ____fput+0x15/0x20 [ 33.105050] task_work_run+0x199/0x270 [ 33.108912] ? task_work_cancel+0x210/0x210 [ 33.113209] ? free_nsproxy+0x185/0x1f0 [ 33.117154] ? switch_task_namespaces+0xa2/0xc0 [ 33.121796] do_exit+0xa52/0x1b40 [ 33.125220] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 33.130208] ? check_noncircular+0x20/0x20 [ 33.134419] ? mm_update_next_owner+0x930/0x930 [ 33.139058] ? __pmd_alloc+0x4e0/0x4e0 [ 33.142926] ? find_held_lock+0x39/0x1d0 [ 33.146968] ? lock_downgrade+0x990/0x990 [ 33.151108] ? handle_mm_fault+0x410/0x8d0 [ 33.155310] ? down_read_trylock+0xdb/0x170 [ 33.159603] ? __handle_mm_fault+0x39c0/0x39c0 [ 33.164154] ? vmacache_find+0x61/0x270 [ 33.168095] ? vmacache_update+0xfe/0x130 [ 33.172217] ? up_read+0x1a/0x40 [ 33.175554] ? __do_page_fault+0x35b/0xb60 [ 33.179755] ? do_vfs_ioctl+0x492/0x1530 [ 33.183793] ? do_page_fault+0xee/0x720 [ 33.187738] ? __do_page_fault+0xb60/0xb60 [ 33.191941] ? putname+0xf3/0x130 [ 33.195369] do_group_exit+0x149/0x400 [ 33.199232] ? lockdep_sys_exit+0x47/0xf0 [ 33.203351] ? SyS_exit+0x30/0x30 [ 33.206778] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 33.211765] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 33.216494] SyS_exit_group+0x1d/0x20 [ 33.220265] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 33.224990] RIP: 0033:0x444db9 [ 33.228156] RSP: 002b:00007ffe19bc6f48 EFLAGS: 00000206 ORIG_RAX: 00000000000000e7 [ 33.235834] RAX: ffffffffffffffda RBX: 00007ffe19bc6f90 RCX: 0000000000444db9 [ 33.243073] RDX: 0000000000444db9 RSI: 0000000020927fd8 RDI: 0000000000000001 [ 33.250313] RBP: 0000000000000082 R08: 0000000000000000 R09: 00007ffe19bc6f90 [ 33.257551] R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000402160 [ 33.264788] R13: 00000000004021f0 R14: 0000000000000000 R15: 0000000000000000 [ 33.272043] [ 33.273639] Allocated by task 2986: [ 33.277235] save_stack_trace+0x16/0x20 [ 33.281179] save_stack+0x43/0xd0 [ 33.284600] kasan_kmalloc+0xad/0xe0 [ 33.288281] __kmalloc_node+0x47/0x70 [ 33.292051] kvmalloc_node+0x64/0xd0 [ 33.295733] alloc_netdev_mqs+0x16e/0xed0 [ 33.299858] __tun_chr_ioctl+0x12be/0x3d20 [ 33.304058] tun_chr_ioctl+0x2a/0x40 [ 33.307739] do_vfs_ioctl+0x1b1/0x1530 [ 33.311593] SyS_ioctl+0x8f/0xc0 [ 33.314926] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 33.319645] [ 33.321240] Freed by task 2986: [ 33.324488] save_stack_trace+0x16/0x20 [ 33.328430] save_stack+0x43/0xd0 [ 33.331850] kasan_slab_free+0x71/0xc0 [ 33.335706] kfree+0xca/0x250 [ 33.338778] kvfree+0x36/0x60 [ 33.341852] free_netdev+0x2cf/0x360 [ 33.345534] __tun_chr_ioctl+0x2cf6/0x3d20 [ 33.349738] tun_chr_ioctl+0x2a/0x40 [ 33.353418] do_vfs_ioctl+0x1b1/0x1530 [ 33.357271] SyS_ioctl+0x8f/0xc0 [ 33.360605] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 33.365323] [ 33.366921] The buggy address belongs to the object at ffff8801cd4e8340 [ 33.366921] which belongs to the cache kmalloc-16384 of size 16384 [ 33.379889] The buggy address is located 13312 bytes inside of [ 33.379889] 16384-byte region [ffff8801cd4e8340, ffff8801cd4ec340) [ 33.392075] The buggy address belongs to the page: [ 33.396972] page:ffffea0007353a00 count:1 mapcount:0 mapping:ffff8801cd4e8340 index:0x0 compound_mapcount: 0 [ 33.406913] flags: 0x200000000008100(slab|head) [ 33.411551] raw: 0200000000008100 ffff8801cd4e8340 0000000000000000 0000000100000001 [ 33.419399] raw: ffffea000737cc20 ffff8801dac01c50 ffff8801dac02200 0000000000000000 [ 33.427245] page dumped because: kasan: bad access detected [ 33.432921] [ 33.434515] Memory state around the buggy address: [ 33.439409] ffff8801cd4eb600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 33.446734] ffff8801cd4eb680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 33.454061] >ffff8801cd4eb700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 33.461384] ^ [ 33.466799] ffff8801cd4eb780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 33.474125] ffff8801cd4eb800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 33.481449] ================================================================== [ 33.488773] Disabling lock debugging due to kernel taint [ 33.494185] Kernel panic - not syncing: panic_on_warn set ... [ 33.494185] [ 33.501509] CPU: 1 PID: 2986 Comm: syzkaller755397 Tainted: G B 4.13.0-next-20170915+ #23 [ 33.510914] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 33.520229] Call Trace: [ 33.522790] dump_stack+0x194/0x257 [ 33.526385] ? arch_local_irq_restore+0x53/0x53 [ 33.531019] ? vprintk_default+0x28/0x30 [ 33.535045] ? detach_if_pending+0x510/0x610 [ 33.539417] panic+0x1e4/0x417 [ 33.542574] ? __warn+0x1d9/0x1d9 [ 33.545996] ? detach_if_pending+0x557/0x610 [ 33.550366] kasan_end_report+0x50/0x50 [ 33.554302] kasan_report+0x137/0x340 [ 33.558067] __asan_report_store8_noabort+0x17/0x20 [ 33.563046] detach_if_pending+0x557/0x610 [ 33.567245] ? trace_raw_output_tick_stop+0x130/0x130 [ 33.572398] ? _raw_spin_lock_irqsave+0x9e/0xc0 [ 33.577028] ? lock_timer_base+0x1a3/0x2b0 [ 33.581224] ? lock_timer_base+0x1eb/0x2b0 [ 33.585422] ? __internal_add_timer+0x2d0/0x2d0 [ 33.590054] ? trace_hardirqs_on+0xd/0x10 [ 33.594167] try_to_del_timer_sync+0xa2/0x120 [ 33.598624] ? del_timer+0x130/0x130 [ 33.602300] ? del_timer_sync+0xeb/0x240 [ 33.606328] del_timer_sync+0x18a/0x240 [ 33.610266] tun_free_netdev+0x105/0x1b0 [ 33.614288] ? tun_xdp+0x410/0x410 [ 33.617789] ? cpumask_next+0x24/0x30 [ 33.621553] ? netdev_refcnt_read+0xed/0x150 [ 33.625923] ? tun_xdp+0x410/0x410 [ 33.629424] netdev_run_todo+0x870/0xca0 [ 33.633448] ? do_group_exit+0x149/0x400 [ 33.637473] ? register_netdev+0x30/0x30 [ 33.641498] ? lock_downgrade+0x990/0x990 [ 33.645609] ? trace_hardirqs_on+0xd/0x10 [ 33.649729] ? refcount_sub_and_test+0x115/0x1b0 [ 33.654447] ? refcount_inc+0x50/0x50 [ 33.658210] ? refcount_inc+0x50/0x50 [ 33.661977] ? sk_destruct+0x4c/0x80 [ 33.665658] ? __sk_free+0x5c/0x230 [ 33.669250] ? sk_free+0x2f/0x40 [ 33.672580] ? __tun_detach+0x176/0x1390 [ 33.676610] ? tun_attach+0xf90/0xf90 [ 33.680378] ? locks_remove_file+0x3fa/0x5a0 [ 33.684751] ? fcntl_setlk+0x10d0/0x10d0 [ 33.688778] ? __fsnotify_parent+0xb4/0x3a0 [ 33.693062] ? fsnotify+0x1af0/0x1af0 [ 33.696829] ? __tun_detach+0x1390/0x1390 [ 33.700942] ? __tun_detach+0x1390/0x1390 [ 33.705053] rtnl_unlock+0xe/0x10 [ 33.708468] tun_chr_close+0x49/0x60 [ 33.712144] __fput+0x333/0x7f0 [ 33.715391] ? fput+0x140/0x140 [ 33.718637] ? check_same_owner+0x320/0x320 [ 33.722924] ____fput+0x15/0x20 [ 33.726166] task_work_run+0x199/0x270 [ 33.730018] ? task_work_cancel+0x210/0x210 [ 33.734302] ? free_nsproxy+0x185/0x1f0 [ 33.738248] ? switch_task_namespaces+0xa2/0xc0 [ 33.742885] do_exit+0xa52/0x1b40 [ 33.746302] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 33.751282] ? check_noncircular+0x20/0x20 [ 33.755484] ? mm_update_next_owner+0x930/0x930 [ 33.760114] ? __pmd_alloc+0x4e0/0x4e0 [ 33.763972] ? find_held_lock+0x39/0x1d0 [ 33.768002] ? lock_downgrade+0x990/0x990 [ 33.772122] ? handle_mm_fault+0x410/0x8d0 [ 33.776320] ? down_read_trylock+0xdb/0x170 [ 33.780603] ? __handle_mm_fault+0x39c0/0x39c0 [ 33.785148] ? vmacache_find+0x61/0x270 [ 33.789084] ? vmacache_update+0xfe/0x130 [ 33.793208] ? up_read+0x1a/0x40 [ 33.796538] ? __do_page_fault+0x35b/0xb60 [ 33.800734] ? do_vfs_ioctl+0x492/0x1530 [ 33.804763] ? do_page_fault+0xee/0x720 [ 33.808700] ? __do_page_fault+0xb60/0xb60 [ 33.812898] ? putname+0xf3/0x130 [ 33.816323] do_group_exit+0x149/0x400 [ 33.820175] ? lockdep_sys_exit+0x47/0xf0 [ 33.824284] ? SyS_exit+0x30/0x30 [ 33.827705] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 33.832685] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 33.837411] SyS_exit_group+0x1d/0x20 [ 33.841175] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 33.845892] RIP: 0033:0x444db9 [ 33.849045] RSP: 002b:00007ffe19bc6f48 EFLAGS: 00000206 ORIG_RAX: 00000000000000e7