====================================================== WARNING: possible circular locking dependency detected 4.15.0-rc3+ #219 Not tainted ------------------------------------------------------ syz-executor6/20517 is trying to acquire lock: (&tty->ldisc_sem){++++}, at: [<00000000f0637350>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 but task is already holding lock: (&pipe->mutex/1){+.+.}, at: [<000000006eb6f76e>] pipe_lock_nested fs/pipe.c:67 [inline] (&pipe->mutex/1){+.+.}, at: [<000000006eb6f76e>] pipe_lock+0x56/0x70 fs/pipe.c:75 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #6 (&pipe->mutex/1){+.+.}: lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4004 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 pipe_lock_nested fs/pipe.c:67 [inline] pipe_lock+0x56/0x70 fs/pipe.c:75 iter_file_splice_write+0x264/0xf30 fs/splice.c:699 do_splice_from fs/splice.c:851 [inline] do_splice fs/splice.c:1147 [inline] SYSC_splice fs/splice.c:1402 [inline] SyS_splice+0x7d5/0x1630 fs/splice.c:1382 entry_SYSCALL_64_fastpath+0x1f/0x96 -> #5 (sb_writers){.+.+}: rq_lock kernel/sched/sched.h:1766 [inline] __schedule+0x24e/0x2060 kernel/sched/core.c:3312 schedule+0xf5/0x430 kernel/sched/core.c:3434 devtmpfsd+0x420/0x4b0 drivers/base/devtmpfs.c:408 kthread+0x37a/0x440 kernel/kthread.c:238 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:441 -> #4 ((completion)&req.done){+.+.}: lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4004 complete_acquire include/linux/completion.h:40 [inline] __wait_for_common kernel/sched/completion.c:109 [inline] wait_for_common kernel/sched/completion.c:123 [inline] wait_for_completion+0xcb/0x7b0 kernel/sched/completion.c:144 devtmpfs_create_node+0x32b/0x4a0 drivers/base/devtmpfs.c:115 device_add+0x120f/0x1640 drivers/base/core.c:1824 device_register+0x1d/0x20 drivers/base/core.c:1905 tty_register_device_attr+0x422/0x740 drivers/tty/tty_io.c:2956 tty_port_register_device_attr_serdev+0x100/0x140 drivers/tty/tty_port.c:166 uart_add_one_port+0xa7a/0x15b0 drivers/tty/serial/serial_core.c:2783 serial8250_register_8250_port+0xfac/0x1990 drivers/tty/serial/8250/8250_core.c:1045 serial_pnp_probe+0x5e7/0xac0 drivers/tty/serial/8250/8250_pnp.c:480 pnp_device_probe+0x15f/0x250 drivers/pnp/driver.c:109 really_probe drivers/base/dd.c:424 [inline] driver_probe_device+0x71b/0xae0 drivers/base/dd.c:566 __driver_attach+0x181/0x1c0 drivers/base/dd.c:800 bus_for_each_dev+0x154/0x1e0 drivers/base/bus.c:313 driver_attach+0x3d/0x50 drivers/base/dd.c:819 bus_add_driver+0x466/0x620 drivers/base/bus.c:669 driver_register+0x1bf/0x3c0 drivers/base/driver.c:168 pnp_register_driver+0x75/0xa0 drivers/pnp/driver.c:272 serial8250_pnp_init+0x15/0x20 drivers/tty/serial/8250/8250_pnp.c:537 serial8250_init+0x8f/0x270 drivers/tty/serial/8250/8250_core.c:1122 do_one_initcall+0x9e/0x330 init/main.c:831 do_initcall_level init/main.c:897 [inline] do_initcalls init/main.c:905 [inline] do_basic_setup init/main.c:923 [inline] kernel_init_freeable+0x469/0x521 init/main.c:1071 kernel_init+0x13/0x172 init/main.c:998 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:441 -> #3 (&port->mutex){+.+.}: lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4004 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 uart_set_termios+0x8f/0x5b0 drivers/tty/serial/serial_core.c:1416 tty_set_termios+0x6d4/0xa40 drivers/tty/tty_ioctl.c:334 set_termios+0x377/0x6b0 drivers/tty/tty_ioctl.c:414 tty_mode_ioctl+0x9fb/0xb10 drivers/tty/tty_ioctl.c:749 n_tty_ioctl_helper+0x40/0x360 drivers/tty/tty_ioctl.c:940 n_tty_ioctl+0x148/0x2d0 drivers/tty/n_tty.c:2435 tty_ioctl+0x32e/0x15f0 drivers/tty/tty_io.c:2638 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:686 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 entry_SYSCALL_64_fastpath+0x1f/0x96 -> #2 (&tty->termios_rwsem){++++}: lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4004 down_write+0x87/0x120 kernel/locking/rwsem.c:70 n_tty_flush_buffer+0x21/0x320 drivers/tty/n_tty.c:357 tty_buffer_flush+0x29a/0x390 drivers/tty/tty_buffer.c:233 tty_ldisc_flush+0x25/0x70 drivers/tty/tty_ldisc.c:418 tty_port_close_start.part.4+0x1cd/0x4e0 drivers/tty/tty_port.c:603 tty_port_close_start drivers/tty/tty_port.c:646 [inline] tty_port_close+0x3f/0x80 drivers/tty/tty_port.c:640 uart_close+0x77/0x1d0 drivers/tty/serial/serial_core.c:1487 tty_release+0x446/0x14c0 drivers/tty/tty_io.c:1639 __fput+0x333/0x7f0 fs/file_table.c:210 ____fput+0x15/0x20 fs/file_table.c:244 task_work_run+0x199/0x270 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x296/0x310 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264 entry_SYSCALL_64_fastpath+0x94/0x96 -> #1 (&buf->lock){+.+.}: lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4004 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 tty_buffer_flush+0xbd/0x390 drivers/tty/tty_buffer.c:222 tty_ldisc_flush+0x25/0x70 drivers/tty/tty_ldisc.c:418 tty_port_close_start.part.4+0x1cd/0x4e0 drivers/tty/tty_port.c:603 tty_port_close_start drivers/tty/tty_port.c:646 [inline] tty_port_close+0x3f/0x80 drivers/tty/tty_port.c:640 uart_close+0x77/0x1d0 drivers/tty/serial/serial_core.c:1487 tty_release+0x446/0x14c0 drivers/tty/tty_io.c:1639 __fput+0x333/0x7f0 fs/file_table.c:210 ____fput+0x15/0x20 fs/file_table.c:244 task_work_run+0x199/0x270 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x296/0x310 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264 entry_SYSCALL_64_fastpath+0x94/0x96 -> #0 (&tty->ldisc_sem){++++}: check_prevs_add kernel/locking/lockdep.c:2031 [inline] validate_chain kernel/locking/lockdep.c:2473 [inline] __lock_acquire+0x3498/0x47f0 kernel/locking/lockdep.c:3500 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4004 __ldsem_down_read_nested+0xd1/0xa90 drivers/tty/tty_ldsem.c:325 ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 tty_ldisc_ref_wait+0x25/0x80 drivers/tty/tty_ldisc.c:277 tty_read+0xf8/0x250 drivers/tty/tty_io.c:852 do_loop_readv_writev fs/read_write.c:673 [inline] do_iter_read+0x3db/0x5b0 fs/read_write.c:897 vfs_readv+0x121/0x1c0 fs/read_write.c:959 kernel_readv fs/splice.c:361 [inline] default_file_splice_read+0x508/0xae0 fs/splice.c:416 do_splice_to+0x110/0x170 fs/splice.c:880 do_splice fs/splice.c:1173 [inline] SYSC_splice fs/splice.c:1402 [inline] SyS_splice+0x11a8/0x1630 fs/splice.c:1382 entry_SYSCALL_64_fastpath+0x1f/0x96 other info that might help us debug this: Chain exists of: &tty->ldisc_sem --> sb_writers --> &pipe->mutex/1 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&pipe->mutex/1); lock(sb_writers); lock(&pipe->mutex/1); lock(&tty->ldisc_sem); *** DEADLOCK *** 1 lock held by syz-executor6/20517: #0: (&pipe->mutex/1){+.+.}, at: [<000000006eb6f76e>] pipe_lock_nested fs/pipe.c:67 [inline] #0: (&pipe->mutex/1){+.+.}, at: [<000000006eb6f76e>] pipe_lock+0x56/0x70 fs/pipe.c:75 stack backtrace: CPU: 0 PID: 20517 Comm: syz-executor6 Not tainted 4.15.0-rc3+ #219 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 print_circular_bug+0x42d/0x610 kernel/locking/lockdep.c:1271 check_prev_add+0x666/0x15f0 kernel/locking/lockdep.c:1914 check_prevs_add kernel/locking/lockdep.c:2031 [inline] validate_chain kernel/locking/lockdep.c:2473 [inline] __lock_acquire+0x3498/0x47f0 kernel/locking/lockdep.c:3500 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4004 __ldsem_down_read_nested+0xd1/0xa90 drivers/tty/tty_ldsem.c:325 ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 tty_ldisc_ref_wait+0x25/0x80 drivers/tty/tty_ldisc.c:277 tty_read+0xf8/0x250 drivers/tty/tty_io.c:852 do_loop_readv_writev fs/read_write.c:673 [inline] do_iter_read+0x3db/0x5b0 fs/read_write.c:897 vfs_readv+0x121/0x1c0 fs/read_write.c:959 kernel_readv fs/splice.c:361 [inline] default_file_splice_read+0x508/0xae0 fs/splice.c:416 do_splice_to+0x110/0x170 fs/splice.c:880 do_splice fs/splice.c:1173 [inline] SYSC_splice fs/splice.c:1402 [inline] SyS_splice+0x11a8/0x1630 fs/splice.c:1382 entry_SYSCALL_64_fastpath+0x1f/0x96 RIP: 0033:0x452a39 RSP: 002b:00007f6c6a393c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000113 RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 0000000000452a39 RDX: 0000000000000014 RSI: 0000000000000000 RDI: 0000000000000015 RBP: 00000000000002dd R08: 0000000000000007 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f2558 R13: 00000000ffffffff R14: 00007f6c6a3946d4 R15: 0000000000000000 QAT: Invalid ioctl QAT: Invalid ioctl QAT: Invalid ioctl QAT: Invalid ioctl audit: type=1400 audit(1513197618.789:1904): avc: denied { ipc_lock } for pid=20617 comm="syz-executor7" capability=14 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1326 audit(1513197618.907:1905): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=20652 comm="syz-executor4" exe="/root/syz-executor4" sig=0 arch=c000003e syscall=202 compat=0 ip=0x452a39 code=0x7ffc0000 audit: type=1326 audit(1513197618.908:1906): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=20652 comm="syz-executor4" exe="/root/syz-executor4" sig=0 arch=c000003e syscall=202 compat=0 ip=0x452a39 code=0x7ffc0000 audit: type=1326 audit(1513197618.909:1907): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=20652 comm="syz-executor4" exe="/root/syz-executor4" sig=0 arch=c000003e syscall=9 compat=0 ip=0x452a39 code=0x7ffc0000 audit: type=1326 audit(1513197618.909:1908): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=20652 comm="syz-executor4" exe="/root/syz-executor4" sig=0 arch=c000003e syscall=202 compat=0 ip=0x452a39 code=0x7ffc0000 audit: type=1326 audit(1513197618.909:1909): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=20652 comm="syz-executor4" exe="/root/syz-executor4" sig=0 arch=c000003e syscall=202 compat=0 ip=0x452a39 code=0x7ffc0000 audit: type=1326 audit(1513197618.909:1910): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=20652 comm="syz-executor4" exe="/root/syz-executor4" sig=0 arch=c000003e syscall=2 compat=0 ip=0x452a39 code=0x7ffc0000 audit: type=1326 audit(1513197618.909:1911): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=20652 comm="syz-executor4" exe="/root/syz-executor4" sig=0 arch=c000003e syscall=202 compat=0 ip=0x452a39 code=0x7ffc0000 netlink: 8 bytes leftover after parsing attributes in process `syz-executor6'. netlink: 8 bytes leftover after parsing attributes in process `syz-executor6'. device gre0 entered promiscuous mode sctp: [Deprecated]: syz-executor1 (pid 20755) Use of int in maxseg socket option. Use struct sctp_assoc_value instead device gre0 entered promiscuous mode sctp: [Deprecated]: syz-executor1 (pid 20768) Use of int in maxseg socket option. Use struct sctp_assoc_value instead netlink: 'syz-executor6': attribute type 4 has an invalid length. device gre0 entered promiscuous mode netlink: 'syz-executor6': attribute type 4 has an invalid length. netlink: 'syz-executor6': attribute type 1 has an invalid length. netlink: 'syz-executor4': attribute type 3 has an invalid length. netlink: 'syz-executor6': attribute type 1 has an invalid length. netlink: 'syz-executor4': attribute type 3 has an invalid length. device lo left promiscuous mode device lo entered promiscuous mode device lo left promiscuous mode sctp: [Deprecated]: syz-executor7 (pid 20977) Use of int in max_burst socket option deprecated. Use struct sctp_assoc_value instead binder_alloc: binder_alloc_mmap_handler: 20971 20005000-20009000 already mapped failed -16 binder: 20971:20973 ioctl c0306201 20007000 returned -14 sctp: [Deprecated]: syz-executor7 (pid 20977) Use of int in max_burst socket option deprecated. Use struct sctp_assoc_value instead netlink: 15 bytes leftover after parsing attributes in process `syz-executor3'. binder_alloc: binder_alloc_mmap_handler: 20971 20005000-20009000 already mapped failed -16 binder: BINDER_SET_CONTEXT_MGR already set binder: 20971:21003 ioctl 40046207 0 returned -16 netlink: 15 bytes leftover after parsing attributes in process `syz-executor3'. sctp: [Deprecated]: syz-executor3 (pid 21033) Use of int in maxseg socket option. Use struct sctp_assoc_value instead sctp: [Deprecated]: syz-executor3 (pid 21057) Use of int in maxseg socket option. Use struct sctp_assoc_value instead netlink: 'syz-executor6': attribute type 2 has an invalid length. netlink: 'syz-executor6': attribute type 2 has an invalid length.