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-mmots-kasan-gce-6,10.128.0.34' (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: [ 39.204435] ================================================================== [ 39.211853] BUG: KASAN: use-after-free in detach_if_pending+0x557/0x610 [ 39.218578] Write of size 8 at addr ffff8801cd4eb740 by task syzkaller477335/2984 [ 39.226168] [ 39.227783] CPU: 0 PID: 2984 Comm: syzkaller477335 Not tainted 4.13.0-mm1+ #7 [ 39.235036] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 39.244364] Call Trace: [ 39.246928] dump_stack+0x194/0x257 [ 39.250535] ? arch_local_irq_restore+0x53/0x53 [ 39.255178] ? show_regs_print_info+0x65/0x65 [ 39.259650] ? lock_timer_base+0x1a3/0x2b0 [ 39.263863] ? detach_if_pending+0x557/0x610 [ 39.268250] print_address_description+0x73/0x250 [ 39.273064] ? detach_if_pending+0x557/0x610 [ 39.277448] kasan_report+0x24e/0x340 [ 39.281225] __asan_report_store8_noabort+0x17/0x20 [ 39.286210] detach_if_pending+0x557/0x610 [ 39.290418] ? trace_raw_output_tick_stop+0x130/0x130 [ 39.295577] ? _raw_spin_lock_irqsave+0x9e/0xc0 [ 39.300212] ? lock_timer_base+0x1a3/0x2b0 [ 39.304418] ? lock_timer_base+0x1eb/0x2b0 [ 39.308628] ? __internal_add_timer+0x2d0/0x2d0 [ 39.313270] ? trace_hardirqs_on+0xd/0x10 [ 39.317397] try_to_del_timer_sync+0xa2/0x120 [ 39.321866] ? del_timer+0x130/0x130 [ 39.325552] ? del_timer_sync+0xeb/0x240 [ 39.329590] del_timer_sync+0x18a/0x240 [ 39.333535] tun_free_netdev+0x105/0x1b0 [ 39.337568] ? tun_xdp+0x410/0x410 [ 39.341075] ? cpumask_next+0x24/0x30 [ 39.344848] ? netdev_refcnt_read+0xed/0x150 [ 39.349229] ? tun_xdp+0x410/0x410 [ 39.352739] netdev_run_todo+0x870/0xca0 [ 39.356780] ? do_group_exit+0x149/0x400 [ 39.360836] ? register_netdev+0x30/0x30 [ 39.364873] ? lock_downgrade+0x990/0x990 [ 39.368995] ? trace_hardirqs_on+0xd/0x10 [ 39.373129] ? refcount_sub_and_test+0x115/0x1b0 [ 39.377856] ? refcount_inc+0x50/0x50 [ 39.381640] ? refcount_inc+0x50/0x50 [ 39.385415] ? sk_destruct+0x4c/0x80 [ 39.389098] ? __sk_free+0x5c/0x230 [ 39.392696] ? sk_free+0x2f/0x40 [ 39.396034] ? __tun_detach+0x176/0x1390 [ 39.400076] ? tun_attach+0xf90/0xf90 [ 39.403852] ? do_raw_spin_trylock+0x190/0x190 [ 39.408409] ? locks_remove_file+0x3fa/0x5a0 [ 39.412793] ? fcntl_setlk+0x10d0/0x10d0 [ 39.416829] ? __fsnotify_parent+0xb4/0x3a0 [ 39.421123] ? fsnotify+0x1af0/0x1af0 [ 39.424909] ? __tun_detach+0x1390/0x1390 [ 39.429028] ? __tun_detach+0x1390/0x1390 [ 39.433149] rtnl_unlock+0xe/0x10 [ 39.436573] tun_chr_close+0x49/0x60 [ 39.440257] __fput+0x333/0x7f0 [ 39.443513] ? fput+0x140/0x140 [ 39.446768] ? check_same_owner+0x320/0x320 [ 39.451068] ? _raw_spin_unlock_irq+0x27/0x70 [ 39.455540] ____fput+0x15/0x20 [ 39.458810] task_work_run+0x199/0x270 [ 39.462672] ? task_work_cancel+0x210/0x210 [ 39.466963] ? _raw_spin_unlock+0x22/0x30 [ 39.471083] ? switch_task_namespaces+0x87/0xc0 [ 39.475728] do_exit+0xa52/0x1b40 [ 39.479152] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 39.484141] ? check_noncircular+0x20/0x20 [ 39.488353] ? mm_update_next_owner+0x930/0x930 [ 39.492991] ? __pmd_alloc+0x4e0/0x4e0 [ 39.496859] ? find_held_lock+0x39/0x1d0 [ 39.500910] ? lock_downgrade+0x990/0x990 [ 39.505049] ? handle_mm_fault+0x410/0x8d0 [ 39.509259] ? down_read_trylock+0xdb/0x170 [ 39.513557] ? __handle_mm_fault+0x39c0/0x39c0 [ 39.518107] ? vmacache_find+0x61/0x270 [ 39.522060] ? up_read+0x1a/0x40 [ 39.525397] ? __do_page_fault+0x35b/0xb60 [ 39.529603] ? do_vfs_ioctl+0x492/0x1530 [ 39.533643] ? do_page_fault+0xee/0x720 [ 39.537589] ? __do_page_fault+0xb60/0xb60 [ 39.541793] ? putname+0xf3/0x130 [ 39.545234] do_group_exit+0x149/0x400 [ 39.549091] ? lockdep_sys_exit+0x47/0xf0 [ 39.553207] ? SyS_exit+0x30/0x30 [ 39.556633] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 39.561633] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 39.566365] SyS_exit_group+0x1d/0x20 [ 39.570139] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 39.574863] RIP: 0033:0x443c58 [ 39.578026] RSP: 002b:00007ffcd9c40ec8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 39.585705] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000443c58 [ 39.592949] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 39.600189] RBP: 0000000000000082 R08: 00000000000000e7 R09: ffffffffffffffd4 [ 39.607429] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 39.614678] R13: 00000000006d6180 R14: 0000000000000000 R15: 0000000000000000 [ 39.621937] [ 39.623537] Allocated by task 2984: [ 39.627136] save_stack_trace+0x16/0x20 [ 39.631083] save_stack+0x43/0xd0 [ 39.634504] kasan_kmalloc+0xad/0xe0 [ 39.638197] __kmalloc_node+0x47/0x70 [ 39.641967] kvmalloc_node+0x64/0xd0 [ 39.645650] alloc_netdev_mqs+0x16e/0xed0 [ 39.649776] __tun_chr_ioctl+0x12be/0x3d20 [ 39.653979] tun_chr_ioctl+0x2a/0x40 [ 39.657662] do_vfs_ioctl+0x1b1/0x1530 [ 39.661517] SyS_ioctl+0x8f/0xc0 [ 39.664855] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 39.669582] [ 39.671177] Freed by task 2984: [ 39.674427] save_stack_trace+0x16/0x20 [ 39.678371] save_stack+0x43/0xd0 [ 39.681793] kasan_slab_free+0x71/0xc0 [ 39.685647] kfree+0xca/0x250 [ 39.688721] kvfree+0x36/0x60 [ 39.692362] free_netdev+0x2cf/0x360 [ 39.696048] __tun_chr_ioctl+0x2cf6/0x3d20 [ 39.700252] tun_chr_ioctl+0x2a/0x40 [ 39.703936] do_vfs_ioctl+0x1b1/0x1530 [ 39.707790] SyS_ioctl+0x8f/0xc0 [ 39.711127] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 39.715849] [ 39.717452] The buggy address belongs to the object at ffff8801cd4e8340 [ 39.717452] which belongs to the cache kmalloc-16384 of size 16384 [ 39.730435] The buggy address is located 13312 bytes inside of [ 39.730435] 16384-byte region [ffff8801cd4e8340, ffff8801cd4ec340) [ 39.742709] The buggy address belongs to the page: [ 39.747607] page:ffffea0007353a00 count:1 mapcount:0 mapping:ffff8801cd4e8340 index:0x0 compound_mapcount: 0 [ 39.757551] flags: 0x200000000008100(slab|head) [ 39.762193] raw: 0200000000008100 ffff8801cd4e8340 0000000000000000 0000000100000001 [ 39.770044] raw: ffffea000733ce20 ffff8801dac01c50 ffff8801dac02200 0000000000000000 [ 39.777890] page dumped because: kasan: bad access detected [ 39.783566] [ 39.785161] Memory state around the buggy address: [ 39.790063] ffff8801cd4eb600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 39.797400] ffff8801cd4eb680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 39.804731] >ffff8801cd4eb700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 39.812057] ^ [ 39.817476] ffff8801cd4eb780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 39.824811] ffff8801cd4eb800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 39.832147] ================================================================== [ 39.839473] Disabling lock debugging due to kernel taint [ 39.844896] Kernel panic - not syncing: panic_on_warn set ... [ 39.844896] [ 39.852222] CPU: 0 PID: 2984 Comm: syzkaller477335 Tainted: G B 4.13.0-mm1+ #7 [ 39.860671] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 39.869989] Call Trace: [ 39.872546] dump_stack+0x194/0x257 [ 39.876138] ? arch_local_irq_restore+0x53/0x53 [ 39.880770] ? vprintk_default+0x28/0x30 [ 39.884799] ? detach_if_pending+0x550/0x610 [ 39.889177] panic+0x1e4/0x417 [ 39.892337] ? __warn+0x1d9/0x1d9 [ 39.895771] ? detach_if_pending+0x557/0x610 [ 39.900320] kasan_end_report+0x50/0x50 [ 39.904258] kasan_report+0x137/0x340 [ 39.908024] __asan_report_store8_noabort+0x17/0x20 [ 39.913003] detach_if_pending+0x557/0x610 [ 39.917203] ? trace_raw_output_tick_stop+0x130/0x130 [ 39.922366] ? _raw_spin_lock_irqsave+0x9e/0xc0 [ 39.927000] ? lock_timer_base+0x1a3/0x2b0 [ 39.931200] ? lock_timer_base+0x1eb/0x2b0 [ 39.935402] ? __internal_add_timer+0x2d0/0x2d0 [ 39.940037] ? trace_hardirqs_on+0xd/0x10 [ 39.944152] try_to_del_timer_sync+0xa2/0x120 [ 39.948611] ? del_timer+0x130/0x130 [ 39.952290] ? del_timer_sync+0xeb/0x240 [ 39.956328] del_timer_sync+0x18a/0x240 [ 39.960268] tun_free_netdev+0x105/0x1b0 [ 39.964387] ? tun_xdp+0x410/0x410 [ 39.967891] ? cpumask_next+0x24/0x30 [ 39.971666] ? netdev_refcnt_read+0xed/0x150 [ 39.976039] ? tun_xdp+0x410/0x410 [ 39.979552] netdev_run_todo+0x870/0xca0 [ 39.983576] ? do_group_exit+0x149/0x400 [ 39.987605] ? register_netdev+0x30/0x30 [ 39.991635] ? lock_downgrade+0x990/0x990 [ 39.995748] ? trace_hardirqs_on+0xd/0x10 [ 39.999869] ? refcount_sub_and_test+0x115/0x1b0 [ 40.004590] ? refcount_inc+0x50/0x50 [ 40.008352] ? refcount_inc+0x50/0x50 [ 40.012117] ? sk_destruct+0x4c/0x80 [ 40.015796] ? __sk_free+0x5c/0x230 [ 40.019388] ? sk_free+0x2f/0x40 [ 40.022720] ? __tun_detach+0x176/0x1390 [ 40.026752] ? tun_attach+0xf90/0xf90 [ 40.030523] ? do_raw_spin_trylock+0x190/0x190 [ 40.035070] ? locks_remove_file+0x3fa/0x5a0 [ 40.039445] ? fcntl_setlk+0x10d0/0x10d0 [ 40.043475] ? __fsnotify_parent+0xb4/0x3a0 [ 40.047762] ? fsnotify+0x1af0/0x1af0 [ 40.051530] ? __tun_detach+0x1390/0x1390 [ 40.055642] ? __tun_detach+0x1390/0x1390 [ 40.059756] rtnl_unlock+0xe/0x10 [ 40.063173] tun_chr_close+0x49/0x60 [ 40.066854] __fput+0x333/0x7f0 [ 40.070101] ? fput+0x140/0x140 [ 40.073349] ? check_same_owner+0x320/0x320 [ 40.077639] ? _raw_spin_unlock_irq+0x27/0x70 [ 40.082102] ____fput+0x15/0x20 [ 40.085348] task_work_run+0x199/0x270 [ 40.089219] ? task_work_cancel+0x210/0x210 [ 40.093509] ? _raw_spin_unlock+0x22/0x30 [ 40.097625] ? switch_task_namespaces+0x87/0xc0 [ 40.102262] do_exit+0xa52/0x1b40 [ 40.105684] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 40.110674] ? check_noncircular+0x20/0x20 [ 40.114886] ? mm_update_next_owner+0x930/0x930 [ 40.119519] ? __pmd_alloc+0x4e0/0x4e0 [ 40.123378] ? find_held_lock+0x39/0x1d0 [ 40.127412] ? lock_downgrade+0x990/0x990 [ 40.131536] ? handle_mm_fault+0x410/0x8d0 [ 40.135736] ? down_read_trylock+0xdb/0x170 [ 40.140022] ? __handle_mm_fault+0x39c0/0x39c0 [ 40.144567] ? vmacache_find+0x61/0x270 [ 40.148510] ? up_read+0x1a/0x40 [ 40.151853] ? __do_page_fault+0x35b/0xb60 [ 40.156052] ? do_vfs_ioctl+0x492/0x1530 [ 40.160084] ? do_page_fault+0xee/0x720 [ 40.164023] ? __do_page_fault+0xb60/0xb60 [ 40.168224] ? putname+0xf3/0x130 [ 40.171645] do_group_exit+0x149/0x400 [ 40.175500] ? lockdep_sys_exit+0x47/0xf0 [ 40.179612] ? SyS_exit+0x30/0x30 [ 40.183032] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 40.188014] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 40.192737] SyS_exit_group+0x1d/0x20 [ 40.196506] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 40.201226] RIP: 0033:0x443c58