sp0: Synchronizing with TNC
------------[ cut here ]------------
======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc3-syzkaller-00044-g2ccbdf43d5e7 #0 Not tainted
------------------------------------------------------
syz-executor.3/6731 is trying to acquire lock:
ffffffff8dac2860 (console_owner){..-.}-{0:0}, at: console_lock_spinning_enable kernel/printk/printk.c:1870 [inline]
ffffffff8dac2860 (console_owner){..-.}-{0:0}, at: console_emit_next_record kernel/printk/printk.c:2922 [inline]
ffffffff8dac2860 (console_owner){..-.}-{0:0}, at: console_flush_all+0x4ff/0xd70 kernel/printk/printk.c:2994

but task is already holding lock:
ffffffff94d61bd8 (&port_lock_key){-.-.}-{2:2}, at: uart_port_lock_irqsave include/linux/serial_core.h:618 [inline]
ffffffff94d61bd8 (&port_lock_key){-.-.}-{2:2}, at: uart_write+0x134/0x3e0 drivers/tty/serial/serial_core.c:624

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&port_lock_key){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
       uart_port_lock_irqsave include/linux/serial_core.h:618 [inline]
       serial8250_console_write+0xaa6/0x1090 drivers/tty/serial/8250/8250_port.c:3352
       console_emit_next_record kernel/printk/printk.c:2928 [inline]
       console_flush_all+0x53f/0xd70 kernel/printk/printk.c:2994
       console_unlock+0xae/0x290 kernel/printk/printk.c:3063
       vprintk_emit kernel/printk/printk.c:2345 [inline]
       vprintk_emit+0x11a/0x5a0 kernel/printk/printk.c:2300
       vprintk+0x7f/0xa0 kernel/printk/printk_safe.c:45
       _printk+0xc8/0x100 kernel/printk/printk.c:2370
       register_console+0xa88/0x10a0 kernel/printk/printk.c:3596
       univ8250_console_init+0x35/0x50 drivers/tty/serial/8250/8250_core.c:719
       console_init+0xcc/0x680 kernel/printk/printk.c:3742
       start_kernel+0x295/0x4c0 init/main.c:1038
       x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:507
       x86_64_start_kernel+0xb2/0xc0 arch/x86/kernel/head64.c:488
       common_startup_64+0x13e/0x148

-> #0 (console_owner){..-.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137
       lock_acquire kernel/locking/lockdep.c:5754 [inline]
       lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719
       console_lock_spinning_enable kernel/printk/printk.c:1870 [inline]
       console_emit_next_record kernel/printk/printk.c:2922 [inline]
       console_flush_all+0x514/0xd70 kernel/printk/printk.c:2994
       console_unlock+0xae/0x290 kernel/printk/printk.c:3063
       vprintk_emit kernel/printk/printk.c:2345 [inline]
       vprintk_emit+0x11a/0x5a0 kernel/printk/printk.c:2300
       vprintk+0x7f/0xa0 kernel/printk/printk_safe.c:45
       _printk+0xc8/0x100 kernel/printk/printk.c:2370
       __report_bug lib/bug.c:195 [inline]
       report_bug+0x4ac/0x580 lib/bug.c:219
       handle_bug+0x3d/0x70 arch/x86/kernel/traps.c:239
       exc_invalid_op+0x17/0x50 arch/x86/kernel/traps.c:260
       asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:621
       uart_write+0x2bf/0x3e0 drivers/tty/serial/serial_core.c:625
       tnc_init drivers/net/hamradio/6pack.c:531 [inline]
       sixpack_open+0x93b/0xb30 drivers/net/hamradio/6pack.c:628
       tty_ldisc_open+0x9c/0x120 drivers/tty/tty_ldisc.c:432
       tty_set_ldisc+0x318/0x720 drivers/tty/tty_ldisc.c:563
       tiocsetd drivers/tty/tty_io.c:2439 [inline]
       tty_ioctl+0xc2e/0x1650 drivers/tty/tty_io.c:2739
       tty_compat_ioctl+0x25c/0x4f0 drivers/tty/tty_io.c:2953
       __do_compat_sys_ioctl+0x2c3/0x330 fs/ioctl.c:1007
       do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
       __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
       do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
       entry_SYSENTER_compat_after_hwframe+0x84/0x8e

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&port_lock_key);
                               lock(console_owner);
                               lock(&port_lock_key);
  lock(console_owner);

 *** DEADLOCK ***

5 locks held by syz-executor.3/6731:
 #0: ffff88801c79c1c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_set_ldisc+0x8b/0x720 drivers/tty/tty_ldisc.c:528
 #1: ffff88801c79c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: __tty_ldisc_lock drivers/tty/tty_ldisc.c:289 [inline]
 #1: ffff88801c79c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_lock+0x65/0xb0 drivers/tty/tty_ldisc.c:313
 #2: ffffffff94d61bd8 (&port_lock_key){-.-.}-{2:2}, at: uart_port_lock_irqsave include/linux/serial_core.h:618 [inline]
 #2: ffffffff94d61bd8 (&port_lock_key){-.-.}-{2:2}, at: uart_write+0x134/0x3e0 drivers/tty/serial/serial_core.c:624
 #3: ffffffff8dba2ca0 (console_lock){+.+.}-{0:0}, at: vprintk+0x7f/0xa0 kernel/printk/printk_safe.c:45
 #4: ffffffff8dba2d10 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:334 [inline]
 #4: ffffffff8dba2d10 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:232 [inline]
 #4: ffffffff8dba2d10 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:286 [inline]
 #4: ffffffff8dba2d10 (console_srcu){....}-{0:0}, at: console_flush_all+0x12d/0xd70 kernel/printk/printk.c:2986

stack backtrace:
CPU: 0 PID: 6731 Comm: syz-executor.3 Not tainted 6.10.0-rc3-syzkaller-00044-g2ccbdf43d5e7 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137
 lock_acquire kernel/locking/lockdep.c:5754 [inline]
 lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719
 console_lock_spinning_enable kernel/printk/printk.c:1870 [inline]
 console_emit_next_record kernel/printk/printk.c:2922 [inline]
 console_flush_all+0x514/0xd70 kernel/printk/printk.c:2994
 console_unlock+0xae/0x290 kernel/printk/printk.c:3063
 vprintk_emit kernel/printk/printk.c:2345 [inline]
 vprintk_emit+0x11a/0x5a0 kernel/printk/printk.c:2300
 vprintk+0x7f/0xa0 kernel/printk/printk_safe.c:45
 _printk+0xc8/0x100 kernel/printk/printk.c:2370
 __report_bug lib/bug.c:195 [inline]
 report_bug+0x4ac/0x580 lib/bug.c:219
 handle_bug+0x3d/0x70 arch/x86/kernel/traps.c:239
 exc_invalid_op+0x17/0x50 arch/x86/kernel/traps.c:260
 asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:621
RIP: 0010:uart_write+0x2bf/0x3e0 drivers/tty/serial/serial_core.c:625
Code: 6f fc e9 4e ff ff ff e8 0f 70 95 fc 90 0f 0b 90 49 c7 c4 d2 ff ff ff e9 39 ff ff ff e8 fa 6f 95 fc 45 31 ff e8 f2 6f 95 fc 90 <0f> 0b 90 48 85 ed 74 8c e8 e4 6f 95 fc 4c 8d a5 08 01 00 00 4c 89
RSP: 0018:ffffc90002df7b88 EFLAGS: 00010046
RAX: 0000000000040000 RBX: ffff88801dbd8be8 RCX: ffffc9000cac1000
RDX: 0000000000040000 RSI: ffffffff84f91fde RDI: ffff88801dbd8f48
RBP: ffffffff94d61bc0 R08: 0000000000000001 R09: fffff520005bef5f
R10: 0000000000000003 R11: 0000000000000004 R12: 0000000000000001
R13: 0000000000000001 R14: ffff8880193fcf01 R15: 0000000000000246
 tnc_init drivers/net/hamradio/6pack.c:531 [inline]
 sixpack_open+0x93b/0xb30 drivers/net/hamradio/6pack.c:628
 tty_ldisc_open+0x9c/0x120 drivers/tty/tty_ldisc.c:432
 tty_set_ldisc+0x318/0x720 drivers/tty/tty_ldisc.c:563
 tiocsetd drivers/tty/tty_io.c:2439 [inline]
 tty_ioctl+0xc2e/0x1650 drivers/tty/tty_io.c:2739
 tty_compat_ioctl+0x25c/0x4f0 drivers/tty/tty_io.c:2953
 __do_compat_sys_ioctl+0x2c3/0x330 fs/ioctl.c:1007
 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
 __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf727e579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f5e705ac EFLAGS: 00000292 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000005423
RDX: 0000000020000040 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
WARNING: CPU: 0 PID: 6731 at drivers/tty/serial/serial_core.c:625 uart_write+0x2bf/0x3e0 drivers/tty/serial/serial_core.c:625
Modules linked in:
CPU: 0 PID: 6731 Comm: syz-executor.3 Not tainted 6.10.0-rc3-syzkaller-00044-g2ccbdf43d5e7 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:uart_write+0x2bf/0x3e0 drivers/tty/serial/serial_core.c:625
Code: 6f fc e9 4e ff ff ff e8 0f 70 95 fc 90 0f 0b 90 49 c7 c4 d2 ff ff ff e9 39 ff ff ff e8 fa 6f 95 fc 45 31 ff e8 f2 6f 95 fc 90 <0f> 0b 90 48 85 ed 74 8c e8 e4 6f 95 fc 4c 8d a5 08 01 00 00 4c 89
RSP: 0018:ffffc90002df7b88 EFLAGS: 00010046
RAX: 0000000000040000 RBX: ffff88801dbd8be8 RCX: ffffc9000cac1000
RDX: 0000000000040000 RSI: ffffffff84f91fde RDI: ffff88801dbd8f48
RBP: ffffffff94d61bc0 R08: 0000000000000001 R09: fffff520005bef5f
R10: 0000000000000003 R11: 0000000000000004 R12: 0000000000000001
R13: 0000000000000001 R14: ffff8880193fcf01 R15: 0000000000000246
FS:  0000000000000000(0000) GS:ffff88802c000000(0063) knlGS:00000000f5e70b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00007fcf9994dff8 CR3: 000000005db5a000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 tnc_init drivers/net/hamradio/6pack.c:531 [inline]
 sixpack_open+0x93b/0xb30 drivers/net/hamradio/6pack.c:628
 tty_ldisc_open+0x9c/0x120 drivers/tty/tty_ldisc.c:432
 tty_set_ldisc+0x318/0x720 drivers/tty/tty_ldisc.c:563
 tiocsetd drivers/tty/tty_io.c:2439 [inline]
 tty_ioctl+0xc2e/0x1650 drivers/tty/tty_io.c:2739
 tty_compat_ioctl+0x25c/0x4f0 drivers/tty/tty_io.c:2953
 __do_compat_sys_ioctl+0x2c3/0x330 fs/ioctl.c:1007
 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
 __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf727e579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f5e705ac EFLAGS: 00000292 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000005423
RDX: 0000000020000040 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	10 06                	adc    %al,(%rsi)
   2:	03 74 b4 01          	add    0x1(%rsp,%rsi,4),%esi
   6:	10 07                	adc    %al,(%rdi)
   8:	03 74 b0 01          	add    0x1(%rax,%rsi,4),%esi
   c:	10 08                	adc    %cl,(%rax)
   e:	03 74 d8 01          	add    0x1(%rax,%rbx,8),%esi
  1e:	00 51 52             	add    %dl,0x52(%rcx)
  21:	55                   	push   %rbp
  22:	89 e5                	mov    %esp,%ebp
  24:	0f 34                	sysenter
  26:	cd 80                	int    $0x80
* 28:	5d                   	pop    %rbp <-- trapping instruction
  29:	5a                   	pop    %rdx
  2a:	59                   	pop    %rcx
  2b:	c3                   	ret
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	90                   	nop
  2f:	90                   	nop
  30:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi
  37:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi