[....] Starting enhanced syslogd: rsyslogd[ 13.606612] audit: type=1400 audit(1548685842.544:4): avc: denied { syslog } for pid=1916 comm="rsyslogd" capability=34 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=capability2 permissive=1 [?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. Starting mcstransd: [....] Starting file context maintaining daemon: restorecond[?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 '10.128.0.197' (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 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program 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: [ 65.144403] ================================================================== [ 65.151842] BUG: KASAN: use-after-free in disk_unblock_events+0x55/0x60 [ 65.158575] Read of size 8 at addr ffff8801d5f82768 by task blkid/2850 [ 65.165210] [ 65.166816] CPU: 0 PID: 2850 Comm: blkid Not tainted 4.4.172+ #13 [ 65.173017] 0000000000000000 089303abceeb137e ffff8801d5b7f730 ffffffff81aacde1 [ 65.181015] 0000000000000000 ffffea000757e000 ffff8801d5f82768 0000000000000008 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 65.189042] 0000000000000000 ffff8801d5b7f768 ffffffff8148fedd 0000000000000000 [ 65.197163] Call Trace: [ 65.199738] [] dump_stack+0xc1/0x120 [ 65.205079] [] print_address_description+0x6f/0x21b [ 65.211725] [] kasan_report.cold+0x8c/0x2be [ 65.217675] [] ? disk_unblock_events+0x55/0x60 [ 65.223879] [] __asan_report_load8_noabort+0x14/0x20 [ 65.230603] [] disk_unblock_events+0x55/0x60 [ 65.236634] [] __blkdev_get+0x70c/0xdf0 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 65.242229] [] ? __blkdev_put+0x840/0x840 [ 65.248000] [] ? trace_hardirqs_on+0x10/0x10 [ 65.254032] [] blkdev_get+0x2e8/0x920 [ 65.259455] [] ? bd_may_claim+0xd0/0xd0 [ 65.265054] [] ? bd_acquire+0x8a/0x370 [ 65.270567] [] ? _raw_spin_unlock+0x2d/0x50 [ 65.276513] [] blkdev_open+0x1aa/0x250 [ 65.282024] [] do_dentry_open+0x38f/0xbd0 [ 65.287798] [] ? __inode_permission2+0x9e/0x250 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 65.294088] [] ? blkdev_get_by_dev+0x80/0x80 [ 65.300132] [] vfs_open+0x10b/0x210 [ 65.305391] [] ? may_open.isra.0+0xe7/0x210 [ 65.311345] [] path_openat+0x136f/0x4470 [ 65.317035] [] ? kasan_kmalloc.part.0+0xc6/0xf0 [ 65.323327] [] ? may_open.isra.0+0x210/0x210 [ 65.329364] [] ? trace_hardirqs_on+0x10/0x10 [ 65.335428] [] do_filp_open+0x1a1/0x270 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 65.341026] [] ? user_path_mountpoint_at+0x50/0x50 [ 65.347580] [] ? __alloc_fd+0x1ea/0x490 [ 65.353179] [] ? _raw_spin_unlock+0x2d/0x50 [ 65.359124] [] do_sys_open+0x2f8/0x600 [ 65.364635] [] ? filp_open+0x70/0x70 [ 65.369973] [] ? retint_user+0x18/0x3c [ 65.375482] [] ? trace_hardirqs_on_caller+0x385/0x5a0 [ 65.382295] [] SyS_open+0x2d/0x40 [ 65.387381] [] entry_SYSCALL_64_fastpath+0x1e/0x9a [ 65.393941] executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 65.395547] Allocated by task 2837: [ 65.399145] [] save_stack_trace+0x26/0x50 [ 65.405040] [] kasan_kmalloc.part.0+0x62/0xf0 [ 65.411290] [] kasan_kmalloc+0xb7/0xd0 [ 65.416930] [] kmem_cache_alloc_trace+0x123/0x2d0 [ 65.423526] [] alloc_disk_node+0x50/0x3c0 [ 65.429424] [] alloc_disk+0x1b/0x20 [ 65.434795] [] loop_add+0x380/0x830 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 65.440176] [] loop_control_ioctl+0x132/0x2f0 [ 65.446417] [] compat_SyS_ioctl+0x403/0x2210 [ 65.452573] [] do_fast_syscall_32+0x32d/0xa90 [ 65.458817] [] sysenter_flags_fixed+0xd/0x1a [ 65.464975] [ 65.466588] Freed by task 2850: [ 65.469842] [] save_stack_trace+0x26/0x50 [ 65.475759] [] kasan_slab_free+0xb0/0x190 [ 65.481665] [] kfree+0xf4/0x310 [ 65.486702] [] disk_release+0x255/0x330 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 65.492472] [] device_release+0x7d/0x220 [ 65.498294] [] kobject_put+0x14c/0x260 [ 65.503931] [] put_disk+0x23/0x30 [ 65.509131] [] __blkdev_get+0x66c/0xdf0 [ 65.514850] [] blkdev_get+0x2e8/0x920 [ 65.520416] [] blkdev_open+0x1aa/0x250 [ 65.526050] [] do_dentry_open+0x38f/0xbd0 [ 65.531953] [] vfs_open+0x10b/0x210 [ 65.537334] [] path_openat+0x136f/0x4470 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 65.543160] [] do_filp_open+0x1a1/0x270 [ 65.548881] [] do_sys_open+0x2f8/0x600 [ 65.554514] [] SyS_open+0x2d/0x40 [ 65.559708] [] entry_SYSCALL_64_fastpath+0x1e/0x9a [ 65.566393] [ 65.568001] The buggy address belongs to the object at ffff8801d5f82200 [ 65.568001] which belongs to the cache kmalloc-2048 of size 2048 [ 65.580802] The buggy address is located 1384 bytes inside of [ 65.580802] 2048-byte region [ffff8801d5f82200, ffff8801d5f82a00) [ 65.592820] The buggy address belongs to the page: [ 65.597806] kasan: CONFIG_KASAN_INLINE enabled