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-5,10.128.15.201' (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: [ 44.444415] ================================================================== [ 44.451891] BUG: KASAN: use-after-free in detach_if_pending+0x557/0x610 [ 44.458620] Write of size 8 at addr ffff8801ce6037c0 by task syzkaller119596/2984 [ 44.466211] [ 44.467816] CPU: 0 PID: 2984 Comm: syzkaller119596 Not tainted 4.13.0+ #73 [ 44.474806] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 44.484137] Call Trace: [ 44.486701] dump_stack+0x194/0x257 [ 44.490308] ? arch_local_irq_restore+0x53/0x53 [ 44.494965] ? show_regs_print_info+0x65/0x65 [ 44.499449] ? lock_timer_base+0x1a3/0x2b0 [ 44.503659] ? detach_if_pending+0x557/0x610 [ 44.508041] print_address_description+0x73/0x250 [ 44.512955] ? detach_if_pending+0x557/0x610 [ 44.517334] kasan_report+0x24e/0x340 [ 44.521129] __asan_report_store8_noabort+0x17/0x20 [ 44.526136] detach_if_pending+0x557/0x610 [ 44.530353] ? __next_timer_interrupt+0x150/0x150 [ 44.535255] ? _raw_spin_lock_irqsave+0x9e/0xc0 [ 44.539979] ? lock_timer_base+0x1a3/0x2b0 [ 44.544186] ? lock_timer_base+0x1eb/0x2b0 [ 44.548397] ? __internal_add_timer+0x2d0/0x2d0 [ 44.553040] ? trace_hardirqs_on+0xd/0x10 [ 44.557179] try_to_del_timer_sync+0xa2/0x120 [ 44.562263] ? del_timer+0x130/0x130 [ 44.565949] ? del_timer_sync+0xeb/0x240 [ 44.570250] del_timer_sync+0x18a/0x240 [ 44.574208] tun_free_netdev+0x105/0x1b0 [ 44.578242] ? tun_xdp+0x410/0x410 [ 44.581756] ? netdev_refcnt_read+0xf4/0x160 [ 44.586141] ? tun_xdp+0x410/0x410 [ 44.589678] netdev_run_todo+0x870/0xca0 [ 44.593716] ? do_group_exit+0x149/0x400 [ 44.597785] ? register_netdev+0x30/0x30 [ 44.602263] ? lock_downgrade+0x990/0x990 [ 44.606409] ? trace_hardirqs_on+0xd/0x10 [ 44.610545] ? refcount_sub_and_test+0x115/0x1b0 [ 44.615274] ? refcount_inc+0x50/0x50 [ 44.619045] ? refcount_inc+0x50/0x50 [ 44.622826] ? sk_destruct+0x4c/0x80 [ 44.626521] ? __sk_free+0x5c/0x230 [ 44.630124] ? sk_free+0x2f/0x40 [ 44.633475] ? __tun_detach+0x176/0x1390 [ 44.637520] ? tun_attach+0xf90/0xf90 [ 44.641299] ? do_raw_spin_trylock+0x190/0x190 [ 44.645856] ? locks_remove_file+0x3fa/0x5a0 [ 44.650343] ? fcntl_setlk+0x10d0/0x10d0 [ 44.654377] ? __fsnotify_parent+0xb4/0x3a0 [ 44.658674] ? fsnotify+0x1af0/0x1af0 [ 44.662462] ? __tun_detach+0x1390/0x1390 [ 44.666580] ? __tun_detach+0x1390/0x1390 [ 44.670812] rtnl_unlock+0xe/0x10 [ 44.674240] tun_chr_close+0x49/0x60 [ 44.677925] __fput+0x333/0x7f0 [ 44.681182] ? fput+0x140/0x140 [ 44.684437] ? check_same_owner+0x320/0x320 [ 44.688732] ? _raw_spin_unlock_irq+0x27/0x70 [ 44.693533] ____fput+0x15/0x20 [ 44.697378] task_work_run+0x199/0x270 [ 44.701249] ? task_work_cancel+0x210/0x210 [ 44.705608] ? _raw_spin_unlock+0x22/0x30 [ 44.709736] ? switch_task_namespaces+0x87/0xc0 [ 44.714385] do_exit+0xa52/0x1b40 [ 44.717814] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 44.722808] ? check_noncircular+0x20/0x20 [ 44.727025] ? mm_update_next_owner+0x930/0x930 [ 44.731670] ? __pmd_alloc+0x4e0/0x4e0 [ 44.735540] ? find_held_lock+0x39/0x1d0 [ 44.739587] ? lock_downgrade+0x990/0x990 [ 44.743729] ? handle_mm_fault+0x4a2/0x860 [ 44.747934] ? down_read_trylock+0xdb/0x170 [ 44.752231] ? __handle_mm_fault+0x3840/0x3840 [ 44.756796] ? vmacache_find+0x61/0x270 [ 44.760754] ? up_read+0x1a/0x40 [ 44.764096] ? __do_page_fault+0x35b/0xb60 [ 44.768339] ? do_vfs_ioctl+0x492/0x1530 [ 44.772382] ? do_page_fault+0xee/0x720 [ 44.776330] ? __do_page_fault+0xb60/0xb60 [ 44.780537] ? putname+0xf3/0x130 [ 44.783970] do_group_exit+0x149/0x400 [ 44.787829] ? lockdep_sys_exit+0x47/0xf0 [ 44.791958] ? SyS_exit+0x30/0x30 [ 44.795393] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 44.800396] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 44.805128] SyS_exit_group+0x1d/0x20 [ 44.808905] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 44.813629] RIP: 0033:0x443658 [ 44.816790] RSP: 002b:00007ffc606a1908 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 44.824471] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000443658 [ 44.831711] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 44.838954] RBP: 0000000000000082 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 44.846197] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 44.853442] R13: 00000000006d6180 R14: 0000000000000000 R15: 0000000000000000 [ 44.860703] [ 44.862313] Allocated by task 2984: [ 44.865919] save_stack_trace+0x16/0x20 [ 44.869870] save_stack+0x43/0xd0 [ 44.873298] kasan_kmalloc+0xad/0xe0 [ 44.876996] __kmalloc_node+0x47/0x70 [ 44.880799] kvmalloc_node+0x64/0xd0 [ 44.884516] alloc_netdev_mqs+0x16e/0xed0 [ 44.888673] __tun_chr_ioctl+0x12be/0x3d40 [ 44.892916] tun_chr_ioctl+0x2a/0x40 [ 44.896614] do_vfs_ioctl+0x1b1/0x1530 [ 44.900480] SyS_ioctl+0x8f/0xc0 [ 44.903826] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 44.908551] [ 44.910165] Freed by task 2984: [ 44.913417] save_stack_trace+0x16/0x20 [ 44.917364] save_stack+0x43/0xd0 [ 44.920787] kasan_slab_free+0x71/0xc0 [ 44.924644] kfree+0xca/0x250 [ 44.927720] kvfree+0x36/0x60 [ 44.930796] free_netdev+0x2cf/0x360 [ 44.934484] __tun_chr_ioctl+0x2cff/0x3d40 [ 44.938687] tun_chr_ioctl+0x2a/0x40 [ 44.942371] do_vfs_ioctl+0x1b1/0x1530 [ 44.946229] SyS_ioctl+0x8f/0xc0 [ 44.949567] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 44.954288] [ 44.955889] The buggy address belongs to the object at ffff8801ce6003c0 [ 44.955889] which belongs to the cache kmalloc-16384 of size 16384 [ 44.968877] The buggy address is located 13312 bytes inside of [ 44.968877] 16384-byte region [ffff8801ce6003c0, ffff8801ce6043c0) [ 44.981070] The buggy address belongs to the page: [ 44.985969] page:ffffea0007398000 count:1 mapcount:0 mapping:ffff8801ce6003c0 index:0x0 compound_mapcount: 0 [ 44.995912] flags: 0x200000000008100(slab|head) [ 45.000639] raw: 0200000000008100 ffff8801ce6003c0 0000000000000000 0000000100000001 [ 45.008495] raw: ffffea000735a420 ffff8801dac01c50 ffff8801dac02200 0000000000000000 [ 45.016348] page dumped because: kasan: bad access detected [ 45.022114] [ 45.023713] Memory state around the buggy address: [ 45.028612] ffff8801ce603680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 45.035960] ffff8801ce603700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 45.043288] >ffff8801ce603780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 45.050617] ^ [ 45.056036] ffff8801ce603800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 45.063372] ffff8801ce603880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 45.070700] ================================================================== [ 45.078029] Disabling lock debugging due to kernel taint [ 45.083442] Kernel panic - not syncing: panic_on_warn set ... [ 45.083442] [ 45.090778] CPU: 0 PID: 2984 Comm: syzkaller119596 Tainted: G B 4.13.0+ #73 [ 45.098969] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 45.108291] Call Trace: [ 45.110847] dump_stack+0x194/0x257 [ 45.114441] ? arch_local_irq_restore+0x53/0x53 [ 45.119093] ? vprintk_default+0x28/0x30 [ 45.123130] ? detach_if_pending+0x470/0x610 [ 45.127509] panic+0x1e4/0x417 [ 45.130665] ? __warn+0x1d9/0x1d9 [ 45.134088] ? detach_if_pending+0x557/0x610 [ 45.138460] kasan_end_report+0x50/0x50 [ 45.142399] kasan_report+0x137/0x340 [ 45.146167] __asan_report_store8_noabort+0x17/0x20 [ 45.151146] detach_if_pending+0x557/0x610 [ 45.155349] ? __next_timer_interrupt+0x150/0x150 [ 45.160159] ? _raw_spin_lock_irqsave+0x9e/0xc0 [ 45.164793] ? lock_timer_base+0x1a3/0x2b0 [ 45.168992] ? lock_timer_base+0x1eb/0x2b0 [ 45.173192] ? __internal_add_timer+0x2d0/0x2d0 [ 45.177827] ? trace_hardirqs_on+0xd/0x10 [ 45.181943] try_to_del_timer_sync+0xa2/0x120 [ 45.186404] ? del_timer+0x130/0x130 [ 45.190094] ? del_timer_sync+0xeb/0x240 [ 45.194122] del_timer_sync+0x18a/0x240 [ 45.198068] tun_free_netdev+0x105/0x1b0 [ 45.202093] ? tun_xdp+0x410/0x410 [ 45.205599] ? netdev_refcnt_read+0xf4/0x160 [ 45.209986] ? tun_xdp+0x410/0x410 [ 45.213494] netdev_run_todo+0x870/0xca0 [ 45.217524] ? do_group_exit+0x149/0x400 [ 45.221557] ? register_netdev+0x30/0x30 [ 45.225587] ? lock_downgrade+0x990/0x990 [ 45.229700] ? trace_hardirqs_on+0xd/0x10 [ 45.233823] ? refcount_sub_and_test+0x115/0x1b0 [ 45.238543] ? refcount_inc+0x50/0x50 [ 45.242308] ? refcount_inc+0x50/0x50 [ 45.246076] ? sk_destruct+0x4c/0x80 [ 45.249753] ? __sk_free+0x5c/0x230 [ 45.253344] ? sk_free+0x2f/0x40 [ 45.256677] ? __tun_detach+0x176/0x1390 [ 45.260709] ? tun_attach+0xf90/0xf90 [ 45.264478] ? do_raw_spin_trylock+0x190/0x190 [ 45.269026] ? locks_remove_file+0x3fa/0x5a0 [ 45.273403] ? fcntl_setlk+0x10d0/0x10d0 [ 45.277438] ? __fsnotify_parent+0xb4/0x3a0 [ 45.281728] ? fsnotify+0x1af0/0x1af0 [ 45.285496] ? __tun_detach+0x1390/0x1390 [ 45.289610] ? __tun_detach+0x1390/0x1390 [ 45.293723] rtnl_unlock+0xe/0x10 [ 45.297139] tun_chr_close+0x49/0x60 [ 45.300818] __fput+0x333/0x7f0 [ 45.304064] ? fput+0x140/0x140 [ 45.307309] ? check_same_owner+0x320/0x320 [ 45.311595] ? _raw_spin_unlock_irq+0x27/0x70 [ 45.316055] ____fput+0x15/0x20 [ 45.319298] task_work_run+0x199/0x270 [ 45.323151] ? task_work_cancel+0x210/0x210 [ 45.327437] ? _raw_spin_unlock+0x22/0x30 [ 45.331549] ? switch_task_namespaces+0x87/0xc0 [ 45.336184] do_exit+0xa52/0x1b40 [ 45.339603] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 45.344583] ? check_noncircular+0x20/0x20 [ 45.348785] ? mm_update_next_owner+0x930/0x930 [ 45.353421] ? __pmd_alloc+0x4e0/0x4e0 [ 45.357277] ? find_held_lock+0x39/0x1d0 [ 45.361310] ? lock_downgrade+0x990/0x990 [ 45.365433] ? handle_mm_fault+0x4a2/0x860 [ 45.369632] ? down_read_trylock+0xdb/0x170 [ 45.373925] ? __handle_mm_fault+0x3840/0x3840 [ 45.378471] ? vmacache_find+0x61/0x270 [ 45.382426] ? up_read+0x1a/0x40 [ 45.385758] ? __do_page_fault+0x35b/0xb60 [ 45.389958] ? do_vfs_ioctl+0x492/0x1530 [ 45.394006] ? do_page_fault+0xee/0x720 [ 45.398031] ? __do_page_fault+0xb60/0xb60 [ 45.402323] ? putname+0xf3/0x130 [ 45.405744] do_group_exit+0x149/0x400 [ 45.409595] ? lockdep_sys_exit+0x47/0xf0 [ 45.413707] ? SyS_exit+0x30/0x30 [ 45.417124] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 45.422107] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 45.426828] SyS_exit_group+0x1d/0x20 [ 45.430593] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 45.435313] RIP: 0033:0x443658 [ 45.438469] RSP: 002b:00007ffc606a1908 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7