[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 60.250849][ T26] audit: type=1800 audit(1560202554.099:25): pid=8317 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 60.271177][ T26] audit: type=1800 audit(1560202554.109:26): pid=8317 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 60.304800][ T26] audit: type=1800 audit(1560202554.109:27): pid=8317 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.15.201' (ECDSA) to the list of known hosts. syzkaller login: [ 72.344179][ T8478] IPVS: ftp: loaded support on port[0] = 21 [ 72.344188][ T8474] IPVS: ftp: loaded support on port[0] = 21 [ 72.357278][ T8480] IPVS: ftp: loaded support on port[0] = 21 [ 72.363831][ T8479] IPVS: ftp: loaded support on port[0] = 21 [ 72.378040][ T8477] IPVS: ftp: loaded support on port[0] = 21 executing program [ 72.405179][ T8481] IPVS: ftp: loaded support on port[0] = 21 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 73.489758][ T8923] ================================================================== [ 73.497998][ T8923] BUG: KASAN: use-after-free in mntput+0x91/0xa0 [ 73.504307][ T8923] Read of size 4 at addr ffff888099134924 by task syz-executor213/8923 [ 73.512514][ T8923] [ 73.514946][ T8923] CPU: 0 PID: 8923 Comm: syz-executor213 Not tainted 5.2.0-rc4 #25 [ 73.522814][ T8923] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 73.532847][ T8923] Call Trace: [ 73.536120][ T8923] dump_stack+0x172/0x1f0 [ 73.540430][ T8923] ? mntput+0x91/0xa0 [ 73.544462][ T8923] print_address_description.cold+0x7c/0x20d [ 73.550423][ T8923] ? mntput+0x91/0xa0 [ 73.554383][ T8923] ? mntput+0x91/0xa0 [ 73.558342][ T8923] __kasan_report.cold+0x1b/0x40 [ 73.563262][ T8923] ? mntput+0x91/0xa0 [ 73.567294][ T8923] kasan_report+0x12/0x20 [ 73.571607][ T8923] __asan_report_load4_noabort+0x14/0x20 [ 73.577213][ T8923] mntput+0x91/0xa0 [ 73.581009][ T8923] path_put+0x50/0x70 [ 73.584971][ T8923] free_fs_struct+0x25/0x70 [ 73.589464][ T8923] exit_fs+0xf0/0x130 [ 73.593423][ T8923] do_exit+0x8e0/0x2fa0 [ 73.597561][ T8923] ? mm_update_next_owner+0x640/0x640 [ 73.602928][ T8923] ? kasan_check_write+0x14/0x20 [ 73.607864][ T8923] ? up_read+0xc4/0x200 [ 73.612000][ T8923] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 73.617440][ T8923] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 73.622876][ T8923] do_group_exit+0x135/0x370 [ 73.627535][ T8923] __x64_sys_exit_group+0x44/0x50 [ 73.632536][ T8923] do_syscall_64+0xfd/0x680 [ 73.637031][ T8923] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 73.642909][ T8923] RIP: 0033:0x43ff48 [ 73.646781][ T8923] Code: 00 00 be 3c 00 00 00 eb 19 66 0f 1f 84 00 00 00 00 00 48 89 d7 89 f0 0f 05 48 3d 00 f0 ff ff 77 21 f4 48 89 d7 44 89 c0 0f 05 <48> 3d 00 f0 ff ff 76 e0 f7 d8 64 41 89 01 eb d8 0f 1f 84 00 00 00 [ 73.666376][ T8923] RSP: 002b:00007ffd444dcf78 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 73.674769][ T8923] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff48 [ 73.682728][ T8923] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 73.690681][ T8923] RBP: 00000000004bfa70 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 73.698648][ T8923] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 73.706599][ T8923] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 73.714557][ T8923] [ 73.716863][ T8923] Allocated by task 8923: [ 73.721172][ T8923] save_stack+0x23/0x90 [ 73.725305][ T8923] __kasan_kmalloc.constprop.0+0xcf/0xe0 [ 73.730916][ T8923] kasan_slab_alloc+0xf/0x20 [ 73.735496][ T8923] kmem_cache_alloc+0x11a/0x6f0 [ 73.740327][ T8923] alloc_vfsmnt+0x28/0x780 [ 73.744734][ T8923] vfs_create_mount+0x96/0x500 [ 73.749479][ T8923] __x64_sys_fsmount+0x584/0xc80 [ 73.754395][ T8923] do_syscall_64+0xfd/0x680 [ 73.758892][ T8923] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 73.764758][ T8923] [ 73.767079][ T8923] Freed by task 9: [ 73.770776][ T8923] save_stack+0x23/0x90 [ 73.774906][ T8923] __kasan_slab_free+0x102/0x150 [ 73.779816][ T8923] kasan_slab_free+0xe/0x10 [ 73.784328][ T8923] kmem_cache_free+0x86/0x260 [ 73.788986][ T8923] free_vfsmnt+0x6f/0x90 [ 73.793226][ T8923] delayed_free_vfsmnt+0x16/0x20 [ 73.798162][ T8923] rcu_core+0xba5/0x1500 [ 73.802385][ T8923] __do_softirq+0x25c/0x94c [ 73.806857][ T8923] [ 73.809277][ T8923] The buggy address belongs to the object at ffff888099134800 [ 73.809277][ T8923] which belongs to the cache mnt_cache of size 432 [ 73.823143][ T8923] The buggy address is located 292 bytes inside of [ 73.823143][ T8923] 432-byte region [ffff888099134800, ffff8880991349b0) [ 73.836399][ T8923] The buggy address belongs to the page: [ 73.842017][ T8923] page:ffffea0002644d00 refcount:1 mapcount:0 mapping:ffff8880aa596940 index:0x0 [ 73.851198][ T8923] flags: 0x1fffc0000000200(slab) [ 73.856114][ T8923] raw: 01fffc0000000200 ffffea0002824648 ffffea00029e78c8 ffff8880aa596940 [ 73.864693][ T8923] raw: 0000000000000000 ffff888099134000 0000000100000008 0000000000000000 [ 73.873334][ T8923] page dumped because: kasan: bad access detected [ 73.879717][ T8923] [ 73.882023][ T8923] Memory state around the buggy address: [ 73.887630][ T8923] ffff888099134800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 73.895670][ T8923] ffff888099134880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 73.903723][ T8923] >ffff888099134900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 73.911765][ T8923] ^ [ 73.916887][ T8923] ffff888099134980: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc [ 73.924928][ T8923] ffff888099134a00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 73.932976][ T8923] ================================================================== [ 73.941042][ T8923] Disabling lock debugging due to kernel taint [ 73.947753][ T8923] Kernel panic - not syncing: panic_on_warn set ... [ 73.954341][ T8923] CPU: 0 PID: 8923 Comm: syz-executor213 Tainted: G B 5.2.0-rc4 #25 [ 73.963594][ T8923] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 73.973622][ T8923] Call Trace: [ 73.976898][ T8923] dump_stack+0x172/0x1f0 [ 73.981240][ T8923] panic+0x2cb/0x744 [ 73.985114][ T8923] ? __warn_printk+0xf3/0xf3 [ 73.989677][ T8923] ? mntput+0x91/0xa0 [ 73.993690][ T8923] ? preempt_schedule+0x4b/0x60 [ 73.998525][ T8923] ? ___preempt_schedule+0x16/0x18 [ 74.003615][ T8923] ? trace_hardirqs_on+0x5e/0x220 [ 74.008613][ T8923] ? mntput+0x91/0xa0 [ 74.012571][ T8923] end_report+0x47/0x4f [ 74.016704][ T8923] ? mntput+0x91/0xa0 [ 74.020661][ T8923] __kasan_report.cold+0xe/0x40 [ 74.025488][ T8923] ? mntput+0x91/0xa0 [ 74.029446][ T8923] kasan_report+0x12/0x20 [ 74.033750][ T8923] __asan_report_load4_noabort+0x14/0x20 [ 74.039357][ T8923] mntput+0x91/0xa0 [ 74.043144][ T8923] path_put+0x50/0x70 [ 74.047108][ T8923] free_fs_struct+0x25/0x70 [ 74.051583][ T8923] exit_fs+0xf0/0x130 [ 74.055543][ T8923] do_exit+0x8e0/0x2fa0 [ 74.059675][ T8923] ? mm_update_next_owner+0x640/0x640 [ 74.065026][ T8923] ? kasan_check_write+0x14/0x20 [ 74.069936][ T8923] ? up_read+0xc4/0x200 [ 74.074068][ T8923] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 74.079502][ T8923] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 74.084936][ T8923] do_group_exit+0x135/0x370 [ 74.089522][ T8923] __x64_sys_exit_group+0x44/0x50 [ 74.094521][ T8923] do_syscall_64+0xfd/0x680 [ 74.099013][ T8923] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 74.104885][ T8923] RIP: 0033:0x43ff48 [ 74.108756][ T8923] Code: 00 00 be 3c 00 00 00 eb 19 66 0f 1f 84 00 00 00 00 00 48 89 d7 89 f0 0f 05 48 3d 00 f0 ff ff 77 21 f4 48 89 d7 44 89 c0 0f 05 <48> 3d 00 f0 ff ff 76 e0 f7 d8 64 41 89 01 eb d8 0f 1f 84 00 00 00 [ 74.128346][ T8923] RSP: 002b:00007ffd444dcf78 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 74.136732][ T8923] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ff48 [ 74.144684][ T8923] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 74.152630][ T8923] RBP: 00000000004bfa70 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 74.160580][ T8923] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 74.168525][ T8923] R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 [ 74.177681][ T8923] Kernel Offset: disabled [ 74.182014][ T8923] Rebooting in 86400 seconds..