[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.885359] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.372899] random: sshd: uninitialized urandom read (32 bytes read) [ 17.775622] random: sshd: uninitialized urandom read (32 bytes read) [ 18.537228] random: sshd: uninitialized urandom read (32 bytes read) [ 18.663326] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.21' (ECDSA) to the list of known hosts. [ 24.123436] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 27.988703] ================================================================== [ 27.996115] BUG: KASAN: use-after-free in disk_unblock_events+0x51/0x60 [ 28.002862] Read of size 8 at addr ffff8801d4ca62e0 by task blkid/4568 [ 28.009509] [ 28.011130] CPU: 0 PID: 4568 Comm: blkid Not tainted 4.9.96-g71fce1e #10 [ 28.017949] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.027290] ffff8801d4fc76d8 ffffffff81eb0b69 ffffea0007532800 ffff8801d4ca62e0 [ 28.035331] 0000000000000000 ffff8801d4ca62e0 0000000000000000 ffff8801d4fc7710 [ 28.043374] ffffffff8156540b ffff8801d4ca62e0 0000000000000008 0000000000000000 [ 28.051403] Call Trace: [ 28.054241] [] dump_stack+0xc1/0x128 [ 28.059594] [] print_address_description+0x6c/0x234 [ 28.066249] [] kasan_report.cold.6+0x242/0x2fe [ 28.072475] [] ? disk_unblock_events+0x51/0x60 [ 28.078698] [] __asan_report_load8_noabort+0x14/0x20 [ 28.085437] [] disk_unblock_events+0x51/0x60 [ 28.091485] [] __blkdev_get+0x6b6/0xd60 [ 28.097101] [] ? __blkdev_put+0x840/0x840 [ 28.102886] [] ? fsnotify+0x114/0x1100 [ 28.108409] [] blkdev_get+0x2da/0x920 [ 28.113850] [] ? bd_may_claim+0xd0/0xd0 [ 28.119459] [] ? bd_acquire+0x27/0x250 [ 28.124982] [] ? bd_acquire+0x88/0x250 [ 28.130510] [] ? _raw_spin_unlock+0x2c/0x50 [ 28.136466] [] blkdev_open+0x1a5/0x250 [ 28.141991] [] do_dentry_open+0x703/0xc80 [ 28.147778] [] ? blkdev_get_by_dev+0x70/0x70 [ 28.153822] [] vfs_open+0x11c/0x210 [ 28.159088] [] ? may_open.isra.57+0x14f/0x2a0 [ 28.165220] [] path_openat+0x758/0x3590 [ 28.170830] [] ? save_stack+0xa9/0xd0 [ 28.176274] [] ? path_lookupat.isra.41+0x410/0x410 [ 28.182845] [] ? __lock_is_held+0xa2/0xf0 [ 28.188630] [] do_filp_open+0x197/0x270 [ 28.194245] [] ? may_open_dev+0xe0/0xe0 [ 28.199860] [] ? _raw_spin_unlock+0x2c/0x50 [ 28.205821] [] ? __alloc_fd+0x1d7/0x4a0 [ 28.211433] [] do_sys_open+0x30d/0x5c0 [ 28.216957] [] ? filp_open+0x70/0x70 [ 28.222315] [] ? up_read+0x1a/0x40 [ 28.227494] [] ? __do_page_fault+0x183/0xd50 [ 28.233538] [] SyS_open+0x2d/0x40 [ 28.238631] [] ? do_sys_open+0x5c0/0x5c0 [ 28.244331] [] do_syscall_64+0x1a6/0x490 [ 28.250030] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.256942] [ 28.258553] Allocated by task 4558: [ 28.262173] save_stack_trace+0x16/0x20 [ 28.266135] save_stack+0x43/0xd0 [ 28.269582] kasan_kmalloc+0xc7/0xe0 [ 28.273283] kmem_cache_alloc_trace+0xfd/0x2b0 [ 28.277852] alloc_disk_node+0x54/0x3a0 [ 28.281811] alloc_disk+0x18/0x20 [ 28.285256] loop_add+0x33b/0x770 [ 28.288693] loop_probe+0x14f/0x180 [ 28.292307] kobj_lookup+0x223/0x410 [ 28.296009] get_gendisk+0x39/0x2d0 [ 28.299626] __blkdev_get+0x351/0xd60 [ 28.303412] blkdev_get+0x488/0x920 [ 28.307024] blkdev_open+0x1a5/0x250 [ 28.310725] do_dentry_open+0x703/0xc80 [ 28.314683] vfs_open+0x11c/0x210 [ 28.318129] path_openat+0x758/0x3590 [ 28.321923] do_filp_open+0x197/0x270 [ 28.325707] do_sys_open+0x30d/0x5c0 [ 28.329404] SyS_open+0x2d/0x40 [ 28.332669] do_syscall_64+0x1a6/0x490 [ 28.336544] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.341624] [ 28.343241] Freed by task 4568: [ 28.346509] save_stack_trace+0x16/0x20 [ 28.350472] save_stack+0x43/0xd0 [ 28.353914] kasan_slab_free+0x72/0xc0 [ 28.357787] kfree+0xfb/0x310 [ 28.360884] disk_release+0x259/0x330 [ 28.364672] device_release+0x7e/0x220 [ 28.368548] kobject_release+0x103/0x1b0 [ 28.372598] kobject_put+0x6d/0xd0 [ 28.376122] put_disk+0x23/0x30 [ 28.379389] __blkdev_get+0x616/0xd60 [ 28.383179] blkdev_get+0x2da/0x920 [ 28.386791] blkdev_open+0x1a5/0x250 [ 28.390491] do_dentry_open+0x703/0xc80 [ 28.394452] vfs_open+0x11c/0x210 [ 28.397894] path_openat+0x758/0x3590 [ 28.401682] do_filp_open+0x197/0x270 [ 28.405469] do_sys_open+0x30d/0x5c0 [ 28.409185] SyS_open+0x2d/0x40 [ 28.412453] do_syscall_64+0x1a6/0x490 [ 28.416328] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.421413] [ 28.423029] The buggy address belongs to the object at ffff8801d4ca5d80 [ 28.423029] which belongs to the cache kmalloc-2048 of size 2048 [ 28.435843] The buggy address is located 1376 bytes inside of [ 28.435843] 2048-byte region [ffff8801d4ca5d80, ffff8801d4ca6580) [ 28.447875] The buggy address belongs to the page: [ 28.452793] page:ffffea0007532800 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 28.462995] flags: 0x8000000000004080(slab|head) [ 28.467742] page dumped because: kasan: bad access detected [ 28.473443] [ 28.475052] Memory state around the buggy address: [ 28.479968] ffff8801d4ca6180: 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 [ 28.487315] ffff8801d4ca6200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 28.494658] >ffff8801d4ca6280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 28.502004] ^ [ 28.508483] ffff8801d4ca6300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 28.515826] ffff8801d4ca6380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 28.523169] ================================================================== [ 28.530508] Disabling lock debugging due to kernel taint executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 28.546511] Kernel panic - not syncing: panic_on_warn set ... [ 28.546511] [ 28.553886] CPU: 0 PID: 4568 Comm: blkid Tainted: G B 4.9.96-g71fce1e #10 [ 28.561919] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.571255] ffff8801d4fc7638 ffffffff81eb0b69 ffffffff841c492d 00000000ffffffff [ 28.579284] 0000000000000000 0000000000000000 0000000000000000 ffff8801d4fc76f8 [ 28.587318] ffffffff8141f975 0000000041b58ab3 ffffffff841b8030 ffffffff8141f7b6 [ 28.595353] Call Trace: [ 28.597932] [] dump_stack+0xc1/0x128 [ 28.603287] [] panic+0x1bf/0x3bc [ 28.608296] [] ? add_taint.cold.6+0x16/0x16 [ 28.614261] [] ? ___preempt_schedule+0x16/0x18 [ 28.620480] [] kasan_end_report+0x47/0x4f [ 28.626268] [] kasan_report.cold.6+0x76/0x2fe [ 28.632412] [] ? disk_unblock_events+0x51/0x60 [ 28.638637] [] __asan_report_load8_noabort+0x14/0x20 [ 28.645373] [] disk_unblock_events+0x51/0x60 [ 28.651423] [] __blkdev_get+0x6b6/0xd60 [ 28.657036] [] ? __blkdev_put+0x840/0x840 [ 28.662822] [] ? fsnotify+0x114/0x1100 [ 28.668349] [] blkdev_get+0x2da/0x920 [ 28.673789] [] ? bd_may_claim+0xd0/0xd0 [ 28.679398] [] ? bd_acquire+0x27/0x250 [ 28.684918] [] ? bd_acquire+0x88/0x250 [ 28.690446] [] ? _raw_spin_unlock+0x2c/0x50 [ 28.696406] [] blkdev_open+0x1a5/0x250 [ 28.701930] [] do_dentry_open+0x703/0xc80 [ 28.707714] [] ? blkdev_get_by_dev+0x70/0x70 [ 28.713757] [] vfs_open+0x11c/0x210 [ 28.719019] [] ? may_open.isra.57+0x14f/0x2a0 [ 28.725150] [] path_openat+0x758/0x3590 [ 28.730765] [] ? save_stack+0xa9/0xd0 [ 28.736211] [] ? path_lookupat.isra.41+0x410/0x410 [ 28.742777] [] ? __lock_is_held+0xa2/0xf0 [ 28.748560] [] do_filp_open+0x197/0x270 [ 28.754175] [] ? may_open_dev+0xe0/0xe0 [ 28.759789] [] ? _raw_spin_unlock+0x2c/0x50 [ 28.765748] [] ? __alloc_fd+0x1d7/0x4a0 [ 28.771362] [] do_sys_open+0x30d/0x5c0 [ 28.776887] [] ? filp_open+0x70/0x70 [ 28.782239] [] ? up_read+0x1a/0x40 [ 28.787418] [] ? __do_page_fault+0x183/0xd50 [ 28.793463] [] SyS_open+0x2d/0x40 [ 28.798560] [] ? do_sys_open+0x5c0/0x5c0 [ 28.804260] [] do_syscall_64+0x1a6/0x490 [ 28.809956] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.817352] Dumping ftrace buffer: [ 28.820871] (ftrace buffer empty) [ 28.824549] Kernel Offset: disabled [ 28.828147] Rebooting in 86400 seconds..