audit: type=1400 audit(1556541777.316:27): avc: denied { getattr } for pid=5856 comm="syz-executor.4" name="NETLINK" dev="sockfs" ino=17864 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=1 INFO: task syz-executor.3:2120 blocked for more than 140 seconds. Not tainted 4.9.170+ #48 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D25064 2120 1 0x00000004 ffff8801c71917c0 ffff8801d2a08580 ffff8801db621000 ffff8801d0612f80 ffff8801db621018 ffff8801acf1fb28 ffffffff82801a4e 0000000041b58ab3 ffff8801acf1faa0 00ffffff81bb61ac ffff8801db6218f0 1ffff100359e3f54 Call Trace: [<000000002fd081cc>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<000000006510cce3>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<00000000fcefb653>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<00000000fcefb653>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<000000001bf5e069>] __lo_release drivers/block/loop.c:1642 [inline] [<000000001bf5e069>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 [<0000000099228eb7>] __blkdev_put+0x461/0x840 fs/block_dev.c:1606 [<00000000fb203839>] blkdev_put+0x88/0x560 fs/block_dev.c:1671 [<000000001caff021>] blkdev_close+0x8b/0xb0 fs/block_dev.c:1678 [<000000002017d37b>] __fput+0x274/0x720 fs/file_table.c:208 [<0000000043e3360a>] ____fput+0x16/0x20 fs/file_table.c:244 [<0000000001d8b3f3>] task_work_run+0x108/0x180 kernel/task_work.c:116 [<00000000f46d7139>] tracehook_notify_resume include/linux/tracehook.h:191 [inline] [<00000000f46d7139>] exit_to_usermode_loop+0x13b/0x160 arch/x86/entry/common.c:162 [<000000006f4964c6>] prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline] [<000000006f4964c6>] syscall_return_slowpath arch/x86/entry/common.c:263 [inline] [<000000006f4964c6>] do_syscall_64+0x3f7/0x570 arch/x86/entry/common.c:290 [<0000000036eb7560>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Showing all locks held in the system: 2 locks held by khungtaskd/24: #0: (rcu_read_lock){......}, at: [<00000000eccbfa54>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<00000000eccbfa54>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<00000000c0240372>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 1 lock held by rsyslogd/1904: #0: (&f->f_pos_lock){+.+.+.}, at: [<0000000002786bad>] __fdget_pos+0xa8/0xd0 fs/file.c:782 2 locks held by getty/2031: #0: (&tty->ldisc_sem){++++++}, at: [<0000000049762e20>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<000000004188ec97>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 3 locks held by syz-executor.3/2120: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000043203c41>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<00000000097ab60e>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664 #2: (loop_ctl_mutex#2){+.+.+.}, at: [<000000001bf5e069>] __lo_release drivers/block/loop.c:1642 [inline] #2: (loop_ctl_mutex#2){+.+.+.}, at: [<000000001bf5e069>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 1 lock held by syz-executor.2/2132: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<000000003f803788>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 1 lock held by syz-executor.1/5073: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<000000003f803788>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 2 locks held by syz-executor.0/5332: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000021445ed5>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000c49d55f6>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.5/5831: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<000000003f803788>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 #1: (&bdev->bd_mutex){+.+.+.}, at: [<00000000a067a2f6>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 2 locks held by blkid/5844: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000021445ed5>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000c49d55f6>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by blkid/5845: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000021445ed5>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.170+ #48 ffff8801d98d7cc8 ffffffff81b4fb21 0000000000000000 0000000000000000 0000000000000000 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00 ffffffff81b5adbc 0000000000000000 0000000000000000 0000000000000000 Call Trace: [<000000005981de63>] __dump_stack lib/dump_stack.c:15 [inline] [<000000005981de63>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<0000000012f214c7>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000c5f0c286>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000019872da>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<000000007e6733fd>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<000000007e6733fd>] check_hung_task kernel/hung_task.c:126 [inline] [<000000007e6733fd>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<000000007e6733fd>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<000000009cddbeda>] kthread+0x278/0x310 kernel/kthread.c:211 [<0000000068ffe15e>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff82810ac2