[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. Starting mcstransd: [ 10.370583] random: sshd: uninitialized urandom read (32 bytes read) [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting file context maintaining daemon: restorecond[?25l[?1c7[ ok 8[?25h[?0c. D[ 11.558565] random: crng init done ebian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.0.55' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 36.851185] ================================================================== [ 36.852774] BUG: KASAN: use-after-free in disk_unblock_events+0x51/0x60 [ 36.853957] Read of size 8 at addr ffff8801cae18de0 by task syz-executor557/2195 [ 36.855400] [ 36.855722] CPU: 0 PID: 2195 Comm: syz-executor557 Not tainted 4.9.141+ #1 [ 36.857022] ffff8801d64cf6f8 ffffffff81b42e79 ffffea00072b8600 ffff8801cae18de0 [ 36.858600] 0000000000000000 ffff8801cae18de0 0000000000000000 ffff8801d64cf730 [ 36.860228] ffffffff815009b8 ffff8801cae18de0 0000000000000008 0000000000000000 [ 36.861845] Call Trace: [ 36.862253] [] dump_stack+0xc1/0x128 [ 36.863423] [] print_address_description+0x6c/0x234 [ 36.864787] [] kasan_report.cold.6+0x242/0x2fe [ 36.866065] [] ? disk_unblock_events+0x51/0x60 [ 36.867226] [] __asan_report_load8_noabort+0x14/0x20 [ 36.868515] [] disk_unblock_events+0x51/0x60 [ 36.869566] [] __blkdev_get+0x6b6/0xd60 [ 36.870644] [] ? __blkdev_put+0x840/0x840 [ 36.873760] [] ? fsnotify+0x114/0x1100 [ 36.879294] [] blkdev_get+0x2da/0x920 [ 36.884746] [] ? debug_lockdep_rcu_enabled+0x77/0x90 [ 36.891502] [] ? bd_may_claim+0xd0/0xd0 [ 36.897131] [] ? bd_acquire+0x27/0x250 [ 36.902670] [] ? bd_acquire+0x88/0x250 [ 36.908210] [] ? _raw_spin_unlock+0x2c/0x50 [ 36.914185] [] blkdev_open+0x1a5/0x250 [ 36.919728] [] do_dentry_open+0x3ef/0xc90 [ 36.925521] [] ? blkdev_get_by_dev+0x70/0x70 [ 36.931577] [] vfs_open+0x11c/0x210 [ 36.936860] [] ? may_open.isra.20+0x14f/0x2a0 [ 36.943015] [] path_openat+0x542/0x2790 [ 36.948655] [] ? path_mountpoint+0x6c0/0x6c0 [ 36.954712] [] ? trace_hardirqs_on+0x10/0x10 [ 36.960799] [] ? expand_files.part.3+0x3a9/0x6d0 [ 36.967205] [] do_filp_open+0x197/0x270 [ 36.972836] [] ? may_open_dev+0xe0/0xe0 [ 36.978457] [] ? _raw_spin_unlock+0x2c/0x50 [ 36.984436] [] ? __alloc_fd+0x1d7/0x4a0 [ 36.990074] [] do_sys_open+0x30d/0x5c0 [ 36.995632] [] ? filp_open+0x70/0x70 [ 37.001005] [] ? up_read+0x1a/0x40 [ 37.006200] [] SyS_open+0x2d/0x40 [ 37.011299] [] ? do_sys_open+0x5c0/0x5c0 [ 37.017011] [] do_syscall_64+0x19f/0x550 [ 37.022725] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 37.029633] [ 37.031244] Allocated by task 2195: [ 37.034883] save_stack_trace+0x16/0x20 [ 37.038864] kasan_kmalloc.part.1+0x62/0xf0 [ 37.043191] kasan_kmalloc+0xaf/0xc0 [ 37.046905] kmem_cache_alloc_trace+0x117/0x2e0 [ 37.051578] alloc_disk_node+0x54/0x3a0 [ 37.055548] alloc_disk+0x18/0x20 [ 37.059001] loop_add+0x368/0x7a0 [ 37.062453] loop_control_ioctl+0x136/0x300 [ 37.066777] do_vfs_ioctl+0x1ac/0x11a0 [ 37.070665] SyS_ioctl+0x8f/0xc0 [ 37.074021] do_syscall_64+0x19f/0x550 [ 37.077899] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 37.082990] [ 37.084614] Freed by task 2195: [ 37.087893] save_stack_trace+0x16/0x20 [ 37.091860] kasan_slab_free+0xac/0x190 [ 37.095823] kfree+0xfb/0x310 [ 37.098926] disk_release+0x259/0x330 [ 37.102713] device_release+0x7e/0x220 [ 37.106598] kobject_put+0x148/0x250 [ 37.110313] put_disk+0x23/0x30 [ 37.113590] __blkdev_get+0x616/0xd60 [ 37.117396] blkdev_get+0x2da/0x920 [ 37.121019] blkdev_open+0x1a5/0x250 [ 37.124730] do_dentry_open+0x3ef/0xc90 [ 37.128701] vfs_open+0x11c/0x210 [ 37.132144] path_openat+0x542/0x2790 [ 37.135928] do_filp_open+0x197/0x270 [ 37.139729] do_sys_open+0x30d/0x5c0 [ 37.143439] SyS_open+0x2d/0x40 [ 37.146717] do_syscall_64+0x19f/0x550 [ 37.150601] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 37.155696] [ 37.157307] The buggy address belongs to the object at ffff8801cae18880 [ 37.157307] which belongs to the cache kmalloc-2048 of size 2048 [ 37.170141] The buggy address is located 1376 bytes inside of [ 37.170141] 2048-byte region [ffff8801cae18880, ffff8801cae19080) [ 37.182202] The buggy address belongs to the page: [ 37.187137] page:ffffea00072b8600 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 37.197377] flags: 0x4000000000004080(slab|head) [ 37.202115] page dumped because: kasan: bad access detected [ 37.207815] [ 37.209431] Memory state around the buggy address: [ 37.214354] ffff8801cae18c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 37.221723] ffff8801cae18d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 37.229075] >ffff8801cae18d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 37.236441] ^ [ 37.242926] ffff8801cae18e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 37.250272] ffff8801cae18e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 37.257629] ================================================================== [ 37.265000] Disabling lock debugging due to kernel taint [ 37.273421] Kernel panic - not syncing: panic_on_warn set ... [ 37.273421] [ 37.280804] CPU: 0 PID: 2195 Comm: syz-executor557 Tainted: G B 4.9.141+ #1 [ 37.289031] ffff8801d64cf658 ffffffff81b42e79 ffffffff82e37630 00000000ffffffff executing program executing program executing program executing program executing program executing program executing program [ 37.297116] 0000000000000000 0000000000000000 0000000000000000 ffff8801d64cf718 [ 37.305182] ffffffff813f7125 0000000041b58ab3 ffffffff82e2b62b ffffffff813f6f66 [ 37.313268] Call Trace: [ 37.315855] [] dump_stack+0xc1/0x128 [ 37.321215] [] panic+0x1bf/0x39f [ 37.326230] [] ? add_taint.cold.5+0x16/0x16 [ 37.332205] [] ? ___preempt_schedule+0x16/0x18 [ 37.338447] [] kasan_end_report+0x47/0x4f [ 37.344243] [] kasan_report.cold.6+0x76/0x2fe executing program executing program executing program executing program executing program executing program executing program [ 37.350397] [] ? disk_unblock_events+0x51/0x60 [ 37.356638] [] __asan_report_load8_noabort+0x14/0x20 [ 37.363406] [] disk_unblock_events+0x51/0x60 [ 37.369493] [] __blkdev_get+0x6b6/0xd60 [ 37.375116] [] ? __blkdev_put+0x840/0x840 [ 37.380913] [] ? fsnotify+0x114/0x1100 [ 37.386450] [] blkdev_get+0x2da/0x920 [ 37.391899] [] ? debug_lockdep_rcu_enabled+0x77/0x90 executing program executing program executing program executing program [ 37.398656] [] ? bd_may_claim+0xd0/0xd0 [ 37.404280] [] ? bd_acquire+0x27/0x250 [ 37.409814] [] ? bd_acquire+0x88/0x250 [ 37.415347] [] ? _raw_spin_unlock+0x2c/0x50 [ 37.421342] [] blkdev_open+0x1a5/0x250 [ 37.426900] [] do_dentry_open+0x3ef/0xc90 [ 37.432700] [] ? blkdev_get_by_dev+0x70/0x70 [ 37.438760] [] vfs_open+0x11c/0x210 [ 37.444042] [] ? may_open.isra.20+0x14f/0x2a0 [ 37.450196] [] path_openat+0x542/0x2790 [ 37.455821] [] ? path_mountpoint+0x6c0/0x6c0 [ 37.461881] [] ? trace_hardirqs_on+0x10/0x10 [ 37.468403] [] ? expand_files.part.3+0x3a9/0x6d0 [ 37.474813] [] do_filp_open+0x197/0x270 [ 37.480452] [] ? may_open_dev+0xe0/0xe0 [ 37.486081] [] ? _raw_spin_unlock+0x2c/0x50 [ 37.492053] [] ? __alloc_fd+0x1d7/0x4a0 [ 37.497682] [] do_sys_open+0x30d/0x5c0 [ 37.503237] [] ? filp_open+0x70/0x70 [ 37.508615] [] ? up_read+0x1a/0x40 [ 37.513813] [] SyS_open+0x2d/0x40 [ 37.518913] [] ? do_sys_open+0x5c0/0x5c0 [ 37.524640] [] do_syscall_64+0x19f/0x550 [ 37.530351] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 37.537602] Kernel Offset: disabled [ 37.541227] Rebooting in 86400 seconds..