====================================================== WARNING: possible circular locking dependency detected 5.10.154 #1 Not tainted ------------------------------------------------------ syz-executor.6/10714 is trying to acquire lock: ffff888047ca4578 (&tty->read_wait){....}-{2:2}, at: __wake_up_common_lock+0xb4/0x140 kernel/sched/wait.c:122 but task is already holding lock: ffff888048e573b8 (&tty->ctrl_lock){....}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:379 [inline] ffff888048e573b8 (&tty->ctrl_lock){....}-{2:2}, at: pty_flush_buffer+0xaf/0x160 drivers/tty/pty.c:223 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&tty->ctrl_lock){....}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x36/0x60 kernel/locking/spinlock.c:159 __proc_set_tty+0x2c/0x620 drivers/tty/tty_jobctrl.c:98 proc_set_tty drivers/tty/tty_jobctrl.c:121 [inline] tiocsctty drivers/tty/tty_jobctrl.c:387 [inline] tty_jobctrl_ioctl+0x582/0xe20 drivers/tty/tty_jobctrl.c:564 tty_ioctl+0x1365/0x1840 drivers/tty/tty_io.c:2737 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x19a/0x210 fs/ioctl.c:739 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xc6 -> #1 (&sighand->siglock){....}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x36/0x60 kernel/locking/spinlock.c:159 __lock_task_sighand+0xd3/0x2f0 kernel/signal.c:1391 lock_task_sighand include/linux/sched/signal.h:693 [inline] task_work_add+0x1df/0x2b0 kernel/task_work.c:58 io_req_task_work_add fs/io_uring.c:2069 [inline] __io_async_wake+0x40b/0x8d0 fs/io_uring.c:4949 __wake_up_common+0x14c/0x4c0 kernel/sched/wait.c:93 __wake_up_common_lock+0xd0/0x140 kernel/sched/wait.c:123 tty_ldisc_lock+0x40/0xb0 drivers/tty/tty_ldisc.c:335 tty_ldisc_hangup+0x204/0x690 drivers/tty/tty_ldisc.c:744 __tty_hangup.part.0+0x510/0x9b0 drivers/tty/tty_io.c:624 __tty_hangup drivers/tty/tty_io.c:574 [inline] tty_vhangup drivers/tty/tty_io.c:697 [inline] tty_ioctl+0x1212/0x1840 drivers/tty/tty_io.c:2683 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x19a/0x210 fs/ioctl.c:739 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xc6 -> #0 (&tty->read_wait){....}-{2:2}: check_prev_add kernel/locking/lockdep.c:2988 [inline] check_prevs_add kernel/locking/lockdep.c:3113 [inline] validate_chain kernel/locking/lockdep.c:3728 [inline] __lock_acquire+0x29e7/0x5b00 kernel/locking/lockdep.c:4954 lock_acquire kernel/locking/lockdep.c:5565 [inline] lock_acquire+0x197/0x490 kernel/locking/lockdep.c:5530 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x36/0x60 kernel/locking/spinlock.c:159 __wake_up_common_lock+0xb4/0x140 kernel/sched/wait.c:122 pty_flush_buffer+0x124/0x160 drivers/tty/pty.c:225 tty_driver_flush_buffer drivers/tty/tty_ioctl.c:95 [inline] __tty_perform_flush+0x149/0x230 drivers/tty/tty_ioctl.c:814 n_tty_ioctl_helper+0x1cb/0x3a0 drivers/tty/tty_ioctl.c:880 n_tty_ioctl+0x56/0x370 drivers/tty/n_tty.c:2516 tty_ioctl+0x912/0x1840 drivers/tty/tty_io.c:2751 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x19a/0x210 fs/ioctl.c:739 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xc6 other info that might help us debug this: Chain exists of: &tty->read_wait --> &sighand->siglock --> &tty->ctrl_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&tty->ctrl_lock); lock(&sighand->siglock); lock(&tty->ctrl_lock); lock(&tty->read_wait); *** DEADLOCK *** 2 locks held by syz-executor.6/10714: #0: ffff888048e57098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x90 drivers/tty/tty_ldisc.c:266 #1: ffff888048e573b8 (&tty->ctrl_lock){....}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:379 [inline] #1: ffff888048e573b8 (&tty->ctrl_lock){....}-{2:2}, at: pty_flush_buffer+0xaf/0x160 drivers/tty/pty.c:223 stack backtrace: CPU: 0 PID: 10714 Comm: syz-executor.6 Not tainted 5.10.154 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x107/0x167 lib/dump_stack.c:118 check_noncircular+0x263/0x2e0 kernel/locking/lockdep.c:2123 check_prev_add kernel/locking/lockdep.c:2988 [inline] check_prevs_add kernel/locking/lockdep.c:3113 [inline] validate_chain kernel/locking/lockdep.c:3728 [inline] __lock_acquire+0x29e7/0x5b00 kernel/locking/lockdep.c:4954 lock_acquire kernel/locking/lockdep.c:5565 [inline] lock_acquire+0x197/0x490 kernel/locking/lockdep.c:5530 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x36/0x60 kernel/locking/spinlock.c:159 __wake_up_common_lock+0xb4/0x140 kernel/sched/wait.c:122 pty_flush_buffer+0x124/0x160 drivers/tty/pty.c:225 tty_driver_flush_buffer drivers/tty/tty_ioctl.c:95 [inline] __tty_perform_flush+0x149/0x230 drivers/tty/tty_ioctl.c:814 n_tty_ioctl_helper+0x1cb/0x3a0 drivers/tty/tty_ioctl.c:880 n_tty_ioctl+0x56/0x370 drivers/tty/n_tty.c:2516 tty_ioctl+0x912/0x1840 drivers/tty/tty_io.c:2751 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x19a/0x210 fs/ioctl.c:739 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xc6 RIP: 0033:0x7f850ef49b19 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f850c4bf188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f850f05cf60 RCX: 00007f850ef49b19 RDX: 0000000000000002 RSI: 000000000000540b RDI: 0000000000000004 RBP: 00007f850efa3f6d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffecba2fd2f R14: 00007f850c4bf300 R15: 0000000000022000 TCP: request_sock_TCPv6: Possible SYN flooding on port 20000. Sending cookies. Check SNMP counters. TCP: request_sock_TCPv6: Possible SYN flooding on port 20000. Sending cookies. Check SNMP counters. cgroup: fork rejected by pids controller in /syz1 nfs4: Unknown parameter '&'@\' nfs4: Unknown parameter '&'@\'