[....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 34.751387] random: sshd: uninitialized urandom read (32 bytes read) [ 35.036819] kauditd_printk_skb: 9 callbacks suppressed [ 35.036826] audit: type=1400 audit(1581425280.984:35): avc: denied { map } for pid=7157 comm="bash" path="/bin/bash" dev="sda1" ino=1457 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 [ 35.093292] random: sshd: uninitialized urandom read (32 bytes read) [ 35.821345] random: sshd: uninitialized urandom read (32 bytes read) [ 42.573055] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.150' (ECDSA) to the list of known hosts. [ 48.081722] 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 [ 48.200550] audit: type=1400 audit(1581425294.154:36): avc: denied { map } for pid=7170 comm="syz-executor114" path="/root/syz-executor114364042" dev="sda1" ino=16483 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 51.082126] ================================================================== [ 51.089633] BUG: KASAN: use-after-free in disk_unblock_events+0x55/0x60 [ 51.096379] Read of size 8 at addr ffff8880954bb848 by task blkid/7402 [ 51.103033] [ 51.104656] CPU: 1 PID: 7402 Comm: blkid Not tainted 4.14.170-syzkaller #0 [ 51.111655] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 51.120997] Call Trace: [ 51.123584] dump_stack+0x142/0x197 [ 51.127204] ? disk_unblock_events+0x55/0x60 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 51.131621] print_address_description.cold+0x7c/0x1dc [ 51.136903] ? disk_unblock_events+0x55/0x60 [ 51.141305] kasan_report.cold+0xa9/0x2af [ 51.145451] __asan_report_load8_noabort+0x14/0x20 [ 51.150380] disk_unblock_events+0x55/0x60 [ 51.154613] __blkdev_get+0x7d6/0x1120 [ 51.158502] ? trace_hardirqs_on+0x10/0x10 [ 51.162829] ? __blkdev_put+0x7f0/0x7f0 [ 51.166800] ? bd_acquire+0x178/0x2c0 [ 51.170602] ? find_held_lock+0x35/0x130 [ 51.174664] blkdev_get+0xa8/0x8e0 [ 51.178209] ? bd_may_claim+0xd0/0xd0 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 51.182012] ? do_raw_spin_unlock+0x174/0x260 [ 51.186509] ? _raw_spin_unlock+0x2d/0x50 [ 51.190661] blkdev_open+0x1d1/0x260 [ 51.194377] ? security_file_open+0x89/0x190 [ 51.198787] do_dentry_open+0x73b/0xeb0 [ 51.202769] ? bd_acquire+0x2c0/0x2c0 [ 51.206574] vfs_open+0x105/0x220 [ 51.210032] path_openat+0x917/0x3e50 [ 51.213833] ? entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 51.219211] ? path_lookupat.isra.0+0x7b0/0x7b0 [ 51.223876] ? find_held_lock+0x35/0x130 [ 51.227938] ? __alloc_fd+0x1d4/0x4a0 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 51.231735] do_filp_open+0x18e/0x250 [ 51.235536] ? may_open_dev+0xe0/0xe0 [ 51.239338] ? do_raw_spin_unlock+0x174/0x260 [ 51.243835] ? _raw_spin_unlock+0x2d/0x50 [ 51.247972] ? __alloc_fd+0x1d4/0x4a0 [ 51.251771] do_sys_open+0x2c5/0x430 [ 51.255487] ? filp_open+0x70/0x70 [ 51.259032] SyS_open+0x2d/0x40 [ 51.262311] ? do_sys_open+0x430/0x430 [ 51.266193] do_syscall_64+0x1e8/0x640 [ 51.270077] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 51.274925] entry_SYSCALL_64_after_hwframe+0x42/0xb7 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 51.280113] RIP: 0033:0x7f5f56b9f120 [ 51.283821] RSP: 002b:00007ffd6391d7e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 [ 51.291525] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f5f56b9f120 [ 51.298792] RDX: 00007ffd6391ff35 RSI: 0000000000000000 RDI: 00007ffd6391ff35 [ 51.306054] RBP: 0000000000000000 R08: 0000000000000078 R09: 0000000000000000 [ 51.313316] R10: 0000000000000000 R11: 0000000000000246 R12: 000000000147b030 [ 51.320580] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000005 [ 51.327847] [ 51.329461] Allocated by task 7368: executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 51.333079] save_stack_trace+0x16/0x20 [ 51.337051] save_stack+0x45/0xd0 [ 51.340496] kasan_kmalloc+0xce/0xf0 [ 51.344207] kmem_cache_alloc_node_trace+0x153/0x770 [ 51.349317] alloc_disk_node+0x64/0x3e0 [ 51.353284] alloc_disk+0x1b/0x20 [ 51.356735] loop_add+0x3e7/0x850 [ 51.360184] loop_control_ioctl+0x1f4/0x2f0 [ 51.364502] do_vfs_ioctl+0x7ae/0x1060 [ 51.368387] SyS_ioctl+0x8f/0xc0 [ 51.371748] do_syscall_64+0x1e8/0x640 [ 51.375635] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 51.380813] executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 51.382434] Freed by task 7402: [ 51.385709] save_stack_trace+0x16/0x20 [ 51.389679] save_stack+0x45/0xd0 [ 51.393124] kasan_slab_free+0x75/0xc0 [ 51.397000] kfree+0xcc/0x270 [ 51.400099] disk_release+0x24b/0x2d0 [ 51.403903] device_release+0xf6/0x1a0 [ 51.407876] kobject_put+0x14e/0x210 [ 51.411589] put_disk+0x23/0x30 [ 51.414863] __blkdev_get+0x73c/0x1120 [ 51.418748] blkdev_get+0xa8/0x8e0 [ 51.422285] blkdev_open+0x1d1/0x260 [ 51.425998] do_dentry_open+0x73b/0xeb0 [ 51.429965] vfs_open+0x105/0x220 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 51.433411] path_openat+0x917/0x3e50 [ 51.437217] do_filp_open+0x18e/0x250 [ 51.441024] do_sys_open+0x2c5/0x430 [ 51.444728] SyS_open+0x2d/0x40 [ 51.447999] do_syscall_64+0x1e8/0x640 [ 51.451981] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 51.457164] [ 51.458802] The buggy address belongs to the object at ffff8880954bb2c0 [ 51.458802] which belongs to the cache kmalloc-2048 of size 2048 [ 51.471624] The buggy address is located 1416 bytes inside of [ 51.471624] 2048-byte region [ffff8880954bb2c0, ffff8880954bbac0) executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 51.483658] The buggy address belongs to the page: [ 51.488579] page:ffffea0002552e80 count:1 mapcount:0 mapping:ffff8880954ba1c0 index:0x0 compound_mapcount: 0 [ 51.498544] flags: 0xfffe0000008100(slab|head) [ 51.503210] raw: 00fffe0000008100 ffff8880954ba1c0 0000000000000000 0000000100000003 [ 51.511087] raw: ffffea0002254c20 ffffea00020714a0 ffff8880aa800c40 0000000000000000 [ 51.518960] page dumped because: kasan: bad access detected [ 51.524659] [ 51.526285] Memory state around the buggy address: executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 51.531211] ffff8880954bb700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 51.538575] ffff8880954bb780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 51.545922] >ffff8880954bb800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 51.553272] ^ [ 51.558976] ffff8880954bb880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 51.566328] ffff8880954bb900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 51.573676] ================================================================== executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 51.581022] 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 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 51.716590] Kernel panic - not syncing: panic_on_warn set ... [ 51.716590] [ 51.723988] CPU: 1 PID: 7402 Comm: blkid Tainted: G B 4.14.170-syzkaller #0 [ 51.732205] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 51.741547] Call Trace: [ 51.744132] dump_stack+0x142/0x197 [ 51.747758] ? disk_unblock_events+0x55/0x60 [ 51.752159] panic+0x1f9/0x42d [ 51.755342] ? add_taint.cold+0x16/0x16 [ 51.759314] ? ___preempt_schedule+0x16/0x18 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 51.763823] kasan_end_report+0x47/0x4f [ 51.767791] kasan_report.cold+0x130/0x2af [ 51.772023] __asan_report_load8_noabort+0x14/0x20 [ 51.776973] disk_unblock_events+0x55/0x60 [ 51.781207] __blkdev_get+0x7d6/0x1120 [ 51.785090] ? trace_hardirqs_on+0x10/0x10 [ 51.789324] ? __blkdev_put+0x7f0/0x7f0 [ 51.793290] ? bd_acquire+0x178/0x2c0 [ 51.797087] ? find_held_lock+0x35/0x130 [ 51.801143] blkdev_get+0xa8/0x8e0 [ 51.804675] ? bd_may_claim+0xd0/0xd0 [ 51.808470] ? do_raw_spin_unlock+0x174/0x260 [ 51.812960] ? _raw_spin_unlock+0x2d/0x50 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 51.817103] blkdev_open+0x1d1/0x260 [ 51.820812] ? security_file_open+0x89/0x190 [ 51.825219] do_dentry_open+0x73b/0xeb0 [ 51.829193] ? bd_acquire+0x2c0/0x2c0 [ 51.832993] vfs_open+0x105/0x220 [ 51.836448] path_openat+0x917/0x3e50 [ 51.840252] ? entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 51.845619] ? path_lookupat.isra.0+0x7b0/0x7b0 [ 51.850281] ? find_held_lock+0x35/0x130 [ 51.854349] ? __alloc_fd+0x1d4/0x4a0 [ 51.858173] do_filp_open+0x18e/0x250 [ 51.861967] ? may_open_dev+0xe0/0xe0 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 51.865763] ? do_raw_spin_unlock+0x174/0x260 [ 51.870256] ? _raw_spin_unlock+0x2d/0x50 [ 51.874401] ? __alloc_fd+0x1d4/0x4a0 [ 51.878207] do_sys_open+0x2c5/0x430 [ 51.881921] ? filp_open+0x70/0x70 [ 51.885459] SyS_open+0x2d/0x40 [ 51.888743] ? do_sys_open+0x430/0x430 [ 51.892626] do_syscall_64+0x1e8/0x640 [ 51.896505] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 51.901345] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 51.906527] RIP: 0033:0x7f5f56b9f120 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 51.910227] RSP: 002b:00007ffd6391d7e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 [ 51.917931] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f5f56b9f120 [ 51.925198] RDX: 00007ffd6391ff35 RSI: 0000000000000000 RDI: 00007ffd6391ff35 [ 51.932461] RBP: 0000000000000000 R08: 0000000000000078 R09: 0000000000000000 [ 51.939723] R10: 0000000000000000 R11: 0000000000000246 R12: 000000000147b030 [ 51.946992] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000005 [ 51.955338] Kernel Offset: disabled [ 51.958958] Rebooting in 86400 seconds..