RBP: 00007f4031b171d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fffbd47650f R14: 00007f4031b17300 R15: 0000000000022000
======================================================
WARNING: possible circular locking dependency detected
5.10.154 #1 Not tainted
------------------------------------------------------
syz-executor.1/49619 is trying to acquire lock:
ffffffff84f0c300 (console_owner){-.-.}-{0:0}, at: console_unlock+0x2e1/0xb40 kernel/printk/printk.c:2507

but task is already holding lock:
ffff888016cb1bd8 (&sighand->siglock){-.-.}-{2:2}, at: __lock_task_sighand+0xd3/0x2f0 kernel/signal.c:1391

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (&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

-> #3 (&tty->read_wait){....}-{2:2}:
       __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
       _raw_spin_lock+0x27/0x40 kernel/locking/spinlock.c:151
       spin_lock include/linux/spinlock.h:354 [inline]
       io_poll_double_wake+0x1f8/0x550 fs/io_uring.c:5062
       __wake_up_common+0x14c/0x4c0 kernel/sched/wait.c:93
       __wake_up_common_lock+0xd0/0x140 kernel/sched/wait.c:123
       tty_ldisc_lock+0x55/0xb0 drivers/tty/tty_ldisc.c:336
       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

-> #2 (&tty->write_wait){-.-.}-{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
       __wake_up_common_lock+0xb4/0x140 kernel/sched/wait.c:122
       tty_port_default_wakeup+0x26/0x40 drivers/tty/tty_port.c:50
       serial8250_tx_chars+0x51f/0xb00 drivers/tty/serial/8250/8250_port.c:1845
       serial8250_handle_irq.part.0+0x3ec/0x4c0 drivers/tty/serial/8250/8250_port.c:1932
       serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1905 [inline]
       serial8250_default_handle_irq+0xb8/0x230 drivers/tty/serial/8250/8250_port.c:1948
       serial8250_interrupt+0xf4/0x1b0 drivers/tty/serial/8250/8250_core.c:127
       __handle_irq_event_percpu+0x2ef/0x820 kernel/irq/handle.c:156
       handle_irq_event_percpu kernel/irq/handle.c:196 [inline]
       handle_irq_event+0xff/0x280 kernel/irq/handle.c:213
       handle_edge_irq+0x249/0xd00 kernel/irq/chip.c:822
       asm_call_irq_on_stack+0x12/0x20
       __run_irq_on_irqstack arch/x86/include/asm/irq_stack.h:48 [inline]
       run_irq_on_irqstack_cond arch/x86/include/asm/irq_stack.h:101 [inline]
       handle_irq arch/x86/kernel/irq.c:230 [inline]
       __common_interrupt arch/x86/kernel/irq.c:249 [inline]
       common_interrupt+0xdd/0x190 arch/x86/kernel/irq.c:239
       asm_common_interrupt+0x1e/0x40 arch/x86/include/asm/idtentry.h:626
       native_restore_fl arch/x86/include/asm/irqflags.h:41 [inline]
       arch_local_irq_restore arch/x86/include/asm/irqflags.h:84 [inline]
       __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
       _raw_spin_unlock_irqrestore+0x25/0x40 kernel/locking/spinlock.c:191
       spin_unlock_irqrestore include/linux/spinlock.h:409 [inline]
       uart_write+0x304/0x580 drivers/tty/serial/serial_core.c:614
       do_output_char+0x5e8/0x870 drivers/tty/n_tty.c:442
       process_output drivers/tty/n_tty.c:509 [inline]
       n_tty_write+0x487/0xf90 drivers/tty/n_tty.c:2395
       do_tty_write drivers/tty/tty_io.c:1028 [inline]
       file_tty_write.constprop.0+0x4f8/0x8d0 drivers/tty/tty_io.c:1118
       redirected_tty_write+0xa5/0xd0 drivers/tty/tty_io.c:1125
       call_write_iter include/linux/fs.h:1904 [inline]
       do_iter_readv_writev+0x476/0x750 fs/read_write.c:740
       do_iter_write+0x191/0x670 fs/read_write.c:866
       vfs_writev+0x1ae/0x5e0 fs/read_write.c:939
       do_writev+0x139/0x300 fs/read_write.c:982
       do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
       entry_SYSCALL_64_after_hwframe+0x61/0xc6

-> #1 (&port_lock_key){-.-.}-{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
       serial8250_console_write+0x9f5/0xc60 drivers/tty/serial/8250/8250_port.c:3333
       call_console_drivers kernel/printk/printk.c:1911 [inline]
       console_unlock+0x82a/0xb40 kernel/printk/printk.c:2532
       register_console kernel/printk/printk.c:2873 [inline]
       register_console+0x53d/0x800 kernel/printk/printk.c:2763
       univ8250_console_init+0x3a/0x4a drivers/tty/serial/8250/8250_core.c:700
       console_init+0x361/0x4fa kernel/printk/printk.c:2983
       start_kernel+0x2e1/0x48e init/main.c:982
       secondary_startup_64_no_verify+0xc2/0xcb

-> #0 (console_owner){-.-.}-{0:0}:
       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
       console_lock_spinning_enable kernel/printk/printk.c:1763 [inline]
       console_unlock+0x360/0xb40 kernel/printk/printk.c:2529
       vprintk_emit+0x1de/0x4d0 kernel/printk/printk.c:2054
       vprintk_func+0x8b/0x140 kernel/printk/printk_safe.c:401
       printk+0xba/0xf1 kernel/printk/printk.c:2102
       fail_dump lib/fault-inject.c:45 [inline]
       should_fail+0x47a/0x5a0 lib/fault-inject.c:146
       should_failslab+0x5/0x20 mm/slab_common.c:1193
       slab_pre_alloc_hook mm/slab.h:515 [inline]
       slab_alloc_node mm/slub.c:2821 [inline]
       slab_alloc mm/slub.c:2904 [inline]
       kmem_cache_alloc+0x5b/0x360 mm/slub.c:2909
       __sigqueue_alloc+0x1ee/0x560 kernel/signal.c:435
       __send_signal+0x5e2/0x1040 kernel/signal.c:1116
       do_send_sig_info kernel/signal.c:1291 [inline]
       group_send_sig_info+0x277/0x2d0 kernel/signal.c:1414
       __kill_pgrp_info+0x88/0x120 kernel/signal.c:1432
       kill_pgrp+0x3a/0x60 kernel/signal.c:1786
       __isig drivers/tty/n_tty.c:1111 [inline]
       isig+0x10a/0x430 drivers/tty/n_tty.c:1128
       n_tty_receive_signal_char+0x1f/0x150 drivers/tty/n_tty.c:1238
       n_tty_receive_char_special+0x1277/0x2aa0 drivers/tty/n_tty.c:1290
       n_tty_receive_buf_standard drivers/tty/n_tty.c:1579 [inline]
       __receive_buf drivers/tty/n_tty.c:1641 [inline]
       n_tty_receive_buf_common+0xa33/0x2b80 drivers/tty/n_tty.c:1737
       tiocsti drivers/tty/tty_io.c:2277 [inline]
       tty_ioctl+0x51b/0x1840 drivers/tty/tty_io.c:2658
       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:
  console_owner --> &tty->read_wait --> &sighand->siglock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&sighand->siglock);
                               lock(&tty->read_wait);
                               lock(&sighand->siglock);
  lock(console_owner);

 *** DEADLOCK ***

6 locks held by syz-executor.1/49619:
 #0: ffff88801ae95098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x90 drivers/tty/tty_ldisc.c:266
 #1: ffff888007c690b8 (&buf->lock){+.+.}-{3:3}, at: tiocsti drivers/tty/tty_io.c:2275 [inline]
 #1: ffff888007c690b8 (&buf->lock){+.+.}-{3:3}, at: tty_ioctl+0x4ae/0x1840 drivers/tty/tty_io.c:2658
 #2: ffff88801ae952e8 (&tty->termios_rwsem){++++}-{3:3}, at: isig+0xe5/0x430 drivers/tty/n_tty.c:1126
 #3: ffffffff84e0a098 (tasklist_lock){.+.?}-{2:2}, at: kill_pgrp+0x1e/0x60 kernel/signal.c:1785
 #4: ffff888016cb1bd8 (&sighand->siglock){-.-.}-{2:2}, at: __lock_task_sighand+0xd3/0x2f0 kernel/signal.c:1391
 #5: ffffffff84fec680 (console_lock){+.+.}-{0:0}, at: vprintk_func+0x8b/0x140 kernel/printk/printk_safe.c:401

stack backtrace:
CPU: 1 PID: 49619 Comm: syz-executor.1 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
 console_lock_spinning_enable kernel/printk/printk.c:1763 [inline]
 console_unlock+0x360/0xb40 kernel/printk/printk.c:2529
 vprintk_emit+0x1de/0x4d0 kernel/printk/printk.c:2054
 vprintk_func+0x8b/0x140 kernel/printk/printk_safe.c:401
 printk+0xba/0xf1 kernel/printk/printk.c:2102
 fail_dump lib/fault-inject.c:45 [inline]
 should_fail+0x47a/0x5a0 lib/fault-inject.c:146
 should_failslab+0x5/0x20 mm/slab_common.c:1193
 slab_pre_alloc_hook mm/slab.h:515 [inline]
 slab_alloc_node mm/slub.c:2821 [inline]
 slab_alloc mm/slub.c:2904 [inline]
 kmem_cache_alloc+0x5b/0x360 mm/slub.c:2909
 __sigqueue_alloc+0x1ee/0x560 kernel/signal.c:435
 __send_signal+0x5e2/0x1040 kernel/signal.c:1116
 do_send_sig_info kernel/signal.c:1291 [inline]
 group_send_sig_info+0x277/0x2d0 kernel/signal.c:1414
 __kill_pgrp_info+0x88/0x120 kernel/signal.c:1432
 kill_pgrp+0x3a/0x60 kernel/signal.c:1786
 __isig drivers/tty/n_tty.c:1111 [inline]
 isig+0x10a/0x430 drivers/tty/n_tty.c:1128
 n_tty_receive_signal_char+0x1f/0x150 drivers/tty/n_tty.c:1238
 n_tty_receive_char_special+0x1277/0x2aa0 drivers/tty/n_tty.c:1290
 n_tty_receive_buf_standard drivers/tty/n_tty.c:1579 [inline]
 __receive_buf drivers/tty/n_tty.c:1641 [inline]
 n_tty_receive_buf_common+0xa33/0x2b80 drivers/tty/n_tty.c:1737
 tiocsti drivers/tty/tty_io.c:2277 [inline]
 tty_ioctl+0x51b/0x1840 drivers/tty/tty_io.c:2658
 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: 0033:0x7f40345a1b19
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:00007f4031b17188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f40346b4f60 RCX: 00007f40345a1b19
RDX: 0000000020001400 RSI: 0000000000005412 RDI: 0000000000000003
RBP: 00007f4031b171d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fffbd47650f R14: 00007f4031b17300 R15: 0000000000022000