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-7,10.128.0.62' (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: [ 44.934346] ================================================================== [ 44.941801] BUG: KASAN: use-after-free in detach_if_pending+0x557/0x610 [ 44.948527] Write of size 8 at addr ffff8801cc943740 by task syzkaller157192/2988 [ 44.956118] [ 44.957722] CPU: 1 PID: 2988 Comm: syzkaller157192 Not tainted 4.13.0-mm1+ #7 [ 44.964976] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 44.974305] Call Trace: [ 44.976870] dump_stack+0x194/0x257 [ 44.980475] ? arch_local_irq_restore+0x53/0x53 [ 44.985120] ? show_regs_print_info+0x65/0x65 [ 44.989597] ? lock_timer_base+0x1a3/0x2b0 [ 44.993809] ? detach_if_pending+0x557/0x610 [ 44.998193] print_address_description+0x73/0x250 [ 45.003010] ? detach_if_pending+0x557/0x610 [ 45.007396] kasan_report+0x24e/0x340 [ 45.011178] __asan_report_store8_noabort+0x17/0x20 [ 45.016167] detach_if_pending+0x557/0x610 [ 45.020379] ? trace_raw_output_tick_stop+0x130/0x130 [ 45.025545] ? _raw_spin_lock_irqsave+0x9e/0xc0 [ 45.030183] ? lock_timer_base+0x1a3/0x2b0 [ 45.034392] ? lock_timer_base+0x1eb/0x2b0 [ 45.038602] ? __internal_add_timer+0x2d0/0x2d0 [ 45.043246] ? trace_hardirqs_on+0xd/0x10 [ 45.047373] try_to_del_timer_sync+0xa2/0x120 [ 45.051840] ? del_timer+0x130/0x130 [ 45.055529] ? del_timer_sync+0xeb/0x240 [ 45.059569] del_timer_sync+0x18a/0x240 [ 45.063520] tun_free_netdev+0x105/0x1b0 [ 45.067553] ? tun_xdp+0x410/0x410 [ 45.071065] ? cpumask_next+0x24/0x30 [ 45.074844] ? netdev_refcnt_read+0xed/0x150 [ 45.079230] ? tun_xdp+0x410/0x410 [ 45.082742] netdev_run_todo+0x870/0xca0 [ 45.086775] ? do_group_exit+0x149/0x400 [ 45.090813] ? register_netdev+0x30/0x30 [ 45.094849] ? lock_downgrade+0x990/0x990 [ 45.098977] ? trace_hardirqs_on+0xd/0x10 [ 45.103133] ? refcount_sub_and_test+0x115/0x1b0 [ 45.107860] ? refcount_inc+0x50/0x50 [ 45.111633] ? refcount_inc+0x50/0x50 [ 45.115411] ? sk_destruct+0x4c/0x80 [ 45.119097] ? __sk_free+0x5c/0x230 [ 45.122697] ? sk_free+0x2f/0x40 [ 45.126035] ? __tun_detach+0x176/0x1390 [ 45.130078] ? tun_attach+0xf90/0xf90 [ 45.133861] ? locks_remove_file+0x3fa/0x5a0 [ 45.138244] ? fcntl_setlk+0x10d0/0x10d0 [ 45.142280] ? __fsnotify_parent+0xb4/0x3a0 [ 45.146577] ? fsnotify+0x1af0/0x1af0 [ 45.150354] ? __tun_detach+0x1390/0x1390 [ 45.154476] ? __tun_detach+0x1390/0x1390 [ 45.158600] rtnl_unlock+0xe/0x10 [ 45.162024] tun_chr_close+0x49/0x60 [ 45.165713] __fput+0x333/0x7f0 [ 45.168977] ? fput+0x140/0x140 [ 45.172232] ? check_same_owner+0x320/0x320 [ 45.176534] ____fput+0x15/0x20 [ 45.179788] task_work_run+0x199/0x270 [ 45.183653] ? task_work_cancel+0x210/0x210 [ 45.187953] ? free_nsproxy+0x185/0x1f0 [ 45.191903] ? switch_task_namespaces+0xa2/0xc0 [ 45.196554] do_exit+0xa52/0x1b40 [ 45.199981] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 45.204971] ? check_noncircular+0x20/0x20 [ 45.209187] ? mm_update_next_owner+0x930/0x930 [ 45.213829] ? __pmd_alloc+0x4e0/0x4e0 [ 45.217699] ? find_held_lock+0x39/0x1d0 [ 45.221743] ? lock_downgrade+0x990/0x990 [ 45.225900] ? handle_mm_fault+0x410/0x8d0 [ 45.230110] ? down_read_trylock+0xdb/0x170 [ 45.234415] ? __handle_mm_fault+0x39c0/0x39c0 [ 45.238972] ? vmacache_find+0x61/0x270 [ 45.242927] ? vmacache_update+0xfe/0x130 [ 45.247053] ? up_read+0x1a/0x40 [ 45.250394] ? __do_page_fault+0x35b/0xb60 [ 45.254601] ? do_vfs_ioctl+0x492/0x1530 [ 45.258646] ? do_page_fault+0xee/0x720 [ 45.262594] ? __do_page_fault+0xb60/0xb60 [ 45.266802] ? putname+0xf3/0x130 [ 45.270232] do_group_exit+0x149/0x400 [ 45.274092] ? lockdep_sys_exit+0x47/0xf0 [ 45.278213] ? SyS_exit+0x30/0x30 [ 45.281641] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 45.286634] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 45.291368] SyS_exit_group+0x1d/0x20 [ 45.295155] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 45.299883] RIP: 0033:0x444ec9 [ 45.303044] RSP: 002b:00007fff62cd5738 EFLAGS: 00000202 ORIG_RAX: 00000000000000e7 [ 45.310727] RAX: ffffffffffffffda RBX: 00007fff62cd5780 RCX: 0000000000444ec9 [ 45.317975] RDX: 0000000000444ec9 RSI: 0000000020115000 RDI: 0000000000000001 [ 45.325219] RBP: 0000000000000082 R08: 0000000000000000 R09: 00007fff62cd5780 [ 45.332461] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000402210 [ 45.339703] R13: 00000000004022a0 R14: 0000000000000000 R15: 0000000000000000 [ 45.346966] [ 45.348567] Allocated by task 2988: [ 45.352170] save_stack_trace+0x16/0x20 [ 45.356115] save_stack+0x43/0xd0 [ 45.359540] kasan_kmalloc+0xad/0xe0 [ 45.363224] __kmalloc_node+0x47/0x70 [ 45.367024] kvmalloc_node+0x64/0xd0 [ 45.370731] alloc_netdev_mqs+0x16e/0xed0 [ 45.374853] __tun_chr_ioctl+0x12be/0x3d20 [ 45.379060] tun_chr_ioctl+0x2a/0x40 [ 45.382751] do_vfs_ioctl+0x1b1/0x1530 [ 45.386610] SyS_ioctl+0x8f/0xc0 [ 45.389957] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 45.394683] [ 45.396286] Freed by task 2988: [ 45.399544] save_stack_trace+0x16/0x20 [ 45.403493] save_stack+0x43/0xd0 [ 45.406917] kasan_slab_free+0x71/0xc0 [ 45.410775] kfree+0xca/0x250 [ 45.413854] kvfree+0x36/0x60 [ 45.416930] free_netdev+0x2cf/0x360 [ 45.420612] __tun_chr_ioctl+0x2cf6/0x3d20 [ 45.424815] tun_chr_ioctl+0x2a/0x40 [ 45.428499] do_vfs_ioctl+0x1b1/0x1530 [ 45.432365] SyS_ioctl+0x8f/0xc0 [ 45.435703] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 45.440424] [ 45.442026] The buggy address belongs to the object at ffff8801cc940340 [ 45.442026] which belongs to the cache kmalloc-16384 of size 16384 [ 45.454998] The buggy address is located 13312 bytes inside of [ 45.454998] 16384-byte region [ffff8801cc940340, ffff8801cc944340) [ 45.467188] The buggy address belongs to the page: [ 45.472092] page:ffffea0007325000 count:1 mapcount:0 mapping:ffff8801cc940340 index:0x0 compound_mapcount: 0 [ 45.482037] flags: 0x200000000008100(slab|head) [ 45.486677] raw: 0200000000008100 ffff8801cc940340 0000000000000000 0000000100000001 [ 45.494527] raw: ffffea000739b620 ffff8801dac01c50 ffff8801dac02200 0000000000000000 [ 45.502373] page dumped because: kasan: bad access detected [ 45.508050] [ 45.509648] Memory state around the buggy address: [ 45.514545] ffff8801cc943600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 45.521875] ffff8801cc943680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 45.529203] >ffff8801cc943700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 45.536531] ^ [ 45.541953] ffff8801cc943780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 45.549284] ffff8801cc943800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 45.556611] ================================================================== [ 45.563936] Disabling lock debugging due to kernel taint [ 45.569349] Kernel panic - not syncing: panic_on_warn set ... [ 45.569349] [ 45.576677] CPU: 1 PID: 2988 Comm: syzkaller157192 Tainted: G B 4.13.0-mm1+ #7 [ 45.585130] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 45.594462] Call Trace: [ 45.597022] dump_stack+0x194/0x257 [ 45.600617] ? arch_local_irq_restore+0x53/0x53 [ 45.605255] ? vprintk_default+0x28/0x30 [ 45.609286] ? detach_if_pending+0x550/0x610 [ 45.613663] panic+0x1e4/0x417 [ 45.616822] ? __warn+0x1d9/0x1d9 [ 45.620247] ? detach_if_pending+0x557/0x610 [ 45.624620] kasan_end_report+0x50/0x50 [ 45.628558] kasan_report+0x137/0x340 [ 45.632326] __asan_report_store8_noabort+0x17/0x20 [ 45.637306] detach_if_pending+0x557/0x610 [ 45.641507] ? trace_raw_output_tick_stop+0x130/0x130 [ 45.646675] ? _raw_spin_lock_irqsave+0x9e/0xc0 [ 45.651307] ? lock_timer_base+0x1a3/0x2b0 [ 45.655519] ? lock_timer_base+0x1eb/0x2b0 [ 45.659720] ? __internal_add_timer+0x2d0/0x2d0 [ 45.664357] ? trace_hardirqs_on+0xd/0x10 [ 45.668473] try_to_del_timer_sync+0xa2/0x120 [ 45.672931] ? del_timer+0x130/0x130 [ 45.676611] ? del_timer_sync+0xeb/0x240 [ 45.680638] del_timer_sync+0x18a/0x240 [ 45.684580] tun_free_netdev+0x105/0x1b0 [ 45.688606] ? tun_xdp+0x410/0x410 [ 45.692111] ? cpumask_next+0x24/0x30 [ 45.695879] ? netdev_refcnt_read+0xed/0x150 [ 45.700254] ? tun_xdp+0x410/0x410 [ 45.703762] netdev_run_todo+0x870/0xca0 [ 45.707788] ? do_group_exit+0x149/0x400 [ 45.711816] ? register_netdev+0x30/0x30 [ 45.715846] ? lock_downgrade+0x990/0x990 [ 45.719961] ? trace_hardirqs_on+0xd/0x10 [ 45.724088] ? refcount_sub_and_test+0x115/0x1b0 [ 45.728810] ? refcount_inc+0x50/0x50 [ 45.732576] ? refcount_inc+0x50/0x50 [ 45.736346] ? sk_destruct+0x4c/0x80 [ 45.740025] ? __sk_free+0x5c/0x230 [ 45.743616] ? sk_free+0x2f/0x40 [ 45.746953] ? __tun_detach+0x176/0x1390 [ 45.750985] ? tun_attach+0xf90/0xf90 [ 45.754756] ? locks_remove_file+0x3fa/0x5a0 [ 45.759131] ? fcntl_setlk+0x10d0/0x10d0 [ 45.763160] ? __fsnotify_parent+0xb4/0x3a0 [ 45.767447] ? fsnotify+0x1af0/0x1af0 [ 45.771214] ? __tun_detach+0x1390/0x1390 [ 45.775329] ? __tun_detach+0x1390/0x1390 [ 45.779444] rtnl_unlock+0xe/0x10 [ 45.782862] tun_chr_close+0x49/0x60 [ 45.786541] __fput+0x333/0x7f0 [ 45.789790] ? fput+0x140/0x140 [ 45.793035] ? check_same_owner+0x320/0x320 [ 45.797324] ____fput+0x15/0x20 [ 45.800573] task_work_run+0x199/0x270 [ 45.804438] ? task_work_cancel+0x210/0x210 [ 45.808741] ? free_nsproxy+0x185/0x1f0 [ 45.812681] ? switch_task_namespaces+0xa2/0xc0 [ 45.817319] do_exit+0xa52/0x1b40 [ 45.820739] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 45.825720] ? check_noncircular+0x20/0x20 [ 45.829926] ? mm_update_next_owner+0x930/0x930 [ 45.834562] ? __pmd_alloc+0x4e0/0x4e0 [ 45.838419] ? find_held_lock+0x39/0x1d0 [ 45.842466] ? lock_downgrade+0x990/0x990 [ 45.846590] ? handle_mm_fault+0x410/0x8d0 [ 45.850788] ? down_read_trylock+0xdb/0x170 [ 45.855076] ? __handle_mm_fault+0x39c0/0x39c0 [ 45.859624] ? vmacache_find+0x61/0x270 [ 45.863563] ? vmacache_update+0xfe/0x130 [ 45.867679] ? up_read+0x1a/0x40 [ 45.871011] ? __do_page_fault+0x35b/0xb60 [ 45.875209] ? do_vfs_ioctl+0x492/0x1530 [ 45.879239] ? do_page_fault+0xee/0x720 [ 45.883178] ? __do_page_fault+0xb60/0xb60 [ 45.887377] ? putname+0xf3/0x130 [ 45.890797] do_group_exit+0x149/0x400 [ 45.894650] ? lockdep_sys_exit+0x47/0xf0 [ 45.898762] ? SyS_exit+0x30/0x30 [ 45.902181] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 45.907165] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 45.911895] SyS_exit_group+0x1d/0x20 [ 45.915664] entry_SYSCALL_64_fastpath+0x1f/0xbe [ 45.920386] RIP: 0033:0x444ec9 [ 45.923543] RSP: 002b:00007fff62cd5738 EFLAGS: 00000202 ORIG_RAX: 00000000000000e7 [ 45.931218] RAX: ffffffffffffffda RBX: 00007fff62cd5780 RCX: 0000000000444ec9