[syzbot] [serial?] possible deadlock in console_trylock_spinning (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8867bbd4a056 mm: arm64: Fix the out-of-bounds issue in con..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=12f1c636980000
kernel config: https://syzkaller.appspot.com/x/.config?x=3b4350cf56c61c80
dashboard link: https://syzkaller.appspot.com/bug?extid=8f689f8825d60fb97dbe
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6ea21f50498b/disk-8867bbd4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e2fed09364aa/vmlinux-8867bbd4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4860173c7a18/Image-8867bbd4.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8f689f...@syzkaller.appspotmail.com

------------[ cut here ]------------
======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc2-syzkaller-g8867bbd4a056 #0 Tainted: G W
------------------------------------------------------
syz-executor.0/7498 is trying to acquire lock:
ffff80008f1bcea0 (console_owner){-.-.}-{0:0}, at: console_trylock_spinning+0x1d4/0x3e0 kernel/printk/printk.c:1977

but task is already holding lock:
ffff800093bc1c58 (&port_lock_key){-.-.}-{2:2}, at: uart_port_lock_irqsave include/linux/serial_core.h:618 [inline]
ffff800093bc1c58 (&port_lock_key){-.-.}-{2:2}, at: uart_write+0x114/0x2ec 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+0x5c/0x7c kernel/locking/spinlock.c:162
uart_port_lock_irqsave include/linux/serial_core.h:618 [inline]
pl011_console_write+0x148/0x724 drivers/tty/serial/amba-pl011.c:2316
console_emit_next_record kernel/printk/printk.c:2928 [inline]
console_flush_all+0x5cc/0xb74 kernel/printk/printk.c:2994
console_unlock+0xec/0x3d4 kernel/printk/printk.c:3063
vprintk_emit+0x1ec/0x350 kernel/printk/printk.c:2345
vprintk_default+0xa0/0xe4 kernel/printk/printk.c:2360
vprintk+0x200/0x2d4 kernel/printk/printk_safe.c:45
_printk+0xdc/0x128 kernel/printk/printk.c:2370
register_console+0x700/0xa8c kernel/printk/printk.c:3596
uart_configure_port drivers/tty/serial/serial_core.c:2664 [inline]
serial_core_add_one_port drivers/tty/serial/serial_core.c:3192 [inline]
serial_core_register_port+0x1428/0x1bf4 drivers/tty/serial/serial_core.c:3429
serial_ctrl_register_port+0x28/0x38 drivers/tty/serial/serial_ctrl.c:41
uart_add_one_port+0x28/0x38 drivers/tty/serial/serial_port.c:136
pl011_register_port+0x1b4/0x44c drivers/tty/serial/amba-pl011.c:2744
sbsa_uart_probe+0x488/0x608 drivers/tty/serial/amba-pl011.c:2914
platform_probe+0x148/0x1c0 drivers/base/platform.c:1404
really_probe+0x38c/0x8fc drivers/base/dd.c:656
__driver_probe_device+0x194/0x374 drivers/base/dd.c:798
driver_probe_device+0x78/0x330 drivers/base/dd.c:828
__device_attach_driver+0x2a8/0x4f4 drivers/base/dd.c:956
bus_for_each_drv+0x228/0x2bc drivers/base/bus.c:457
__device_attach+0x2b4/0x434 drivers/base/dd.c:1028
device_initial_probe+0x24/0x34 drivers/base/dd.c:1077
bus_probe_device+0x178/0x240 drivers/base/bus.c:532
device_add+0x728/0xa6c drivers/base/core.c:3721
platform_device_add+0x3e8/0x6e8 drivers/base/platform.c:716
platform_device_register_full+0x4ec/0x604 drivers/base/platform.c:844
acpi_create_platform_device+0x5bc/0x744 drivers/acpi/acpi_platform.c:177
acpi_default_enumeration+0x6c/0xdc drivers/acpi/scan.c:2184
acpi_bus_attach+0x8b8/0xaa8 drivers/acpi/scan.c:2293
acpi_dev_for_one_check+0xa0/0xb4 drivers/acpi/bus.c:1143
device_for_each_child+0xec/0x174 drivers/base/core.c:4050
acpi_dev_for_each_child+0xc4/0x108 drivers/acpi/bus.c:1155
acpi_bus_attach+0x358/0xaa8 drivers/acpi/scan.c:2298
acpi_dev_for_one_check+0xa0/0xb4 drivers/acpi/bus.c:1143
device_for_each_child+0xec/0x174 drivers/base/core.c:4050
acpi_dev_for_each_child+0xc4/0x108 drivers/acpi/bus.c:1155
acpi_bus_attach+0x358/0xaa8 drivers/acpi/scan.c:2298
acpi_bus_scan+0x118/0x4f0 drivers/acpi/scan.c:2579
acpi_scan_init+0x214/0x6b0 drivers/acpi/scan.c:2714
acpi_init+0x190/0x254 drivers/acpi/bus.c:1460
do_one_initcall+0x254/0x9e4 init/main.c:1267
do_initcall_level+0x154/0x214 init/main.c:1329
do_initcalls+0x58/0xac init/main.c:1345
do_basic_setup+0x8c/0xa0 init/main.c:1364
kernel_init_freeable+0x324/0x478 init/main.c:1578
kernel_init+0x24/0x2a0 init/main.c:1467
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860

-> #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+0x3384/0x763c kernel/locking/lockdep.c:5137
lock_acquire+0x248/0x73c kernel/locking/lockdep.c:5754
console_trylock_spinning+0x200/0x3e0 kernel/printk/printk.c:1994
vprintk_emit+0x1d0/0x350 kernel/printk/printk.c:2344
vprintk_default+0xa0/0xe4 kernel/printk/printk.c:2360
vprintk+0x200/0x2d4 kernel/printk/printk_safe.c:45
_printk+0xdc/0x128 kernel/printk/printk.c:2370
__report_bug lib/bug.c:195 [inline]
report_bug+0x3b8/0x5b0 lib/bug.c:219
bug_handler+0x50/0x1fc arch/arm64/kernel/traps.c:978
call_break_hook arch/arm64/kernel/debug-monitors.c:321 [inline]
brk_handler+0x17c/0x2e0 arch/arm64/kernel/debug-monitors.c:328
do_debug_exception+0x1e4/0x398 arch/arm64/mm/fault.c:909
el1_dbg+0x64/0x80 arch/arm64/kernel/entry-common.c:472
el1h_64_sync_handler+0x40/0xac arch/arm64/kernel/entry-common.c:512
el1h_64_sync+0x64/0x68 arch/arm64/kernel/entry.S:593
spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
uart_port_unlock_irqrestore include/linux/serial_core.h:669 [inline]
uart_write+0x280/0x2ec drivers/tty/serial/serial_core.c:626
tnc_init drivers/net/hamradio/6pack.c:531 [inline]
sixpack_open+0x5d8/0x8b0 drivers/net/hamradio/6pack.c:628
tty_ldisc_open+0x9c/0x14c drivers/tty/tty_ldisc.c:432
tty_set_ldisc+0x2f8/0x4e0 drivers/tty/tty_ldisc.c:563
tiocsetd+0x100/0x13c drivers/tty/tty_io.c:2439
tty_ioctl+0xba0/0xd8c drivers/tty/tty_io.c:2739
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:907 [inline]
__se_sys_ioctl fs/ioctl.c:893 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:893
__invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

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 ***

3 locks held by syz-executor.0/7498:
#0: ffff0000d7eb91c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_lock+0x78/0xc8 drivers/tty/tty_mutex.c:18
#1: ffff0000d7eb90a0 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_write+0x3c/0x4c drivers/tty/tty_ldsem.c:366
#2: ffff800093bc1c58 (&port_lock_key){-.-.}-{2:2}, at: uart_port_lock_irqsave include/linux/serial_core.h:618 [inline]
#2: ffff800093bc1c58 (&port_lock_key){-.-.}-{2:2}, at: uart_write+0x114/0x2ec drivers/tty/serial/serial_core.c:624

stack backtrace:
CPU: 1 PID: 7498 Comm: syz-executor.0 Tainted: G W 6.10.0-rc2-syzkaller-g8867bbd4a056 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Call trace:
dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:317
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:324
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:114
dump_stack+0x1c/0x28 lib/dump_stack.c:123
print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2060
check_noncircular+0x310/0x404 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+0x3384/0x763c kernel/locking/lockdep.c:5137
lock_acquire+0x248/0x73c kernel/locking/lockdep.c:5754
console_trylock_spinning+0x200/0x3e0 kernel/printk/printk.c:1994
vprintk_emit+0x1d0/0x350 kernel/printk/printk.c:2344
vprintk_default+0xa0/0xe4 kernel/printk/printk.c:2360
vprintk+0x200/0x2d4 kernel/printk/printk_safe.c:45
_printk+0xdc/0x128 kernel/printk/printk.c:2370
__report_bug lib/bug.c:195 [inline]
report_bug+0x3b8/0x5b0 lib/bug.c:219
bug_handler+0x50/0x1fc arch/arm64/kernel/traps.c:978
call_break_hook arch/arm64/kernel/debug-monitors.c:321 [inline]
brk_handler+0x17c/0x2e0 arch/arm64/kernel/debug-monitors.c:328
do_debug_exception+0x1e4/0x398 arch/arm64/mm/fault.c:909


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