netlink: 232 bytes leftover after parsing attributes in process `syz-executor.6'.
netlink: 232 bytes leftover after parsing attributes in process `syz-executor.6'.
======================================================
WARNING: possible circular locking dependency detected
5.10.123 #1 Not tainted
------------------------------------------------------
syz-executor.4/22321 is trying to acquire lock:
ffff8880457c4a18 (&sighand->siglock){-.-.}-{2:2}, at: __lock_task_sighand+0xd3/0x2f0 kernel/signal.c:1391

but task is already holding lock:
ffff888045b28578 (&tty->read_wait){....}-{2:2}, at: __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:122

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&tty->read_wait){....}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x36/0x50 kernel/locking/spinlock.c:159
       __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:122
       pty_flush_buffer+0x124/0x160 drivers/tty/pty.c:235
       tty_driver_flush_buffer drivers/tty/tty_ioctl.c:95 [inline]
       __tty_perform_flush+0x145/0x220 drivers/tty/tty_ioctl.c:814
       n_tty_ioctl_helper+0x1c7/0x3a0 drivers/tty/tty_ioctl.c:880
       n_tty_ioctl+0x56/0x370 drivers/tty/n_tty.c:2516
       tty_ioctl+0x912/0x1830 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+0x196/0x210 fs/ioctl.c:739
       do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
       entry_SYSCALL_64_after_hwframe+0x44/0xa9

-> #1 (&tty->ctrl_lock){....}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x36/0x50 kernel/locking/spinlock.c:159
       __proc_set_tty+0x2c/0x610 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+0x57e/0xe10 drivers/tty/tty_jobctrl.c:564
       tty_ioctl+0x1361/0x1830 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+0x196/0x210 fs/ioctl.c:739
       do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
       entry_SYSCALL_64_after_hwframe+0x44/0xa9

-> #0 (&sighand->siglock){-.-.}-{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+0x29e3/0x5b00 kernel/locking/lockdep.c:4954
       lock_acquire kernel/locking/lockdep.c:5564 [inline]
       lock_acquire+0x197/0x490 kernel/locking/lockdep.c:5529
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x36/0x50 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+0x1db/0x2b0 kernel/task_work.c:58
       io_req_task_work_add fs/io_uring.c:2062 [inline]
       __io_async_wake+0x40b/0x8d0 fs/io_uring.c:4938
       __wake_up_common+0x14c/0x4c0 kernel/sched/wait.c:93
       __wake_up_common_lock+0xd0/0x130 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+0x120e/0x1830 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+0x196/0x210 fs/ioctl.c:739
       do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
       entry_SYSCALL_64_after_hwframe+0x44/0xa9

other info that might help us debug this:

Chain exists of:
  &sighand->siglock --> &tty->ctrl_lock --> &tty->read_wait

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

3 locks held by syz-executor.4/22321:
 #0: ffff888045b281c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_lock+0xbd/0x120 drivers/tty/tty_mutex.c:19
 #1: ffff888045b28578 (&tty->read_wait){....}-{2:2}, at: __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:122
 #2: ffffffff84df7460 (rcu_read_lock){....}-{1:2}, at: __lock_task_sighand+0x0/0x2f0 kernel/signal.c:1353

stack backtrace:
CPU: 1 PID: 22321 Comm: syz-executor.4 Not tainted 5.10.123 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:118
 check_noncircular+0x25f/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+0x29e3/0x5b00 kernel/locking/lockdep.c:4954
 lock_acquire kernel/locking/lockdep.c:5564 [inline]
 lock_acquire+0x197/0x490 kernel/locking/lockdep.c:5529
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x36/0x50 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+0x1db/0x2b0 kernel/task_work.c:58
 io_req_task_work_add fs/io_uring.c:2062 [inline]
 __io_async_wake+0x40b/0x8d0 fs/io_uring.c:4938
 __wake_up_common+0x14c/0x4c0 kernel/sched/wait.c:93
 __wake_up_common_lock+0xd0/0x130 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+0x120e/0x1830 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+0x196/0x210 fs/ioctl.c:739
 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f9baf739b19
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:00007f9baccaf188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f9baf84cf60 RCX: 00007f9baf739b19
RDX: 0000000000000000 RSI: 0000000000005437 RDI: 0000000000000004
RBP: 00007f9baf793f6d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe25fe6a8f R14: 00007f9baccaf300 R15: 0000000000022000
9pnet: p9_fd_create_tcp (22547): problem connecting socket to 127.0.0.1
kmemleak: 91 new suspected memory leaks (see /sys/kernel/debug/kmemleak)