possible deadlock in console_lock_spinning_enable

From: syzbot
Date: Thu Jun 20 2019 - 07:22:22 EST

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Hello,

syzbot found the following crash on:

HEAD commit: bed3c0d8 Merge tag 'for-5.2-rc5-tag' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=175d674ea00000
kernel config: https://syzkaller.appspot.com/x/.config?x=28ec3437a5394ee0
dashboard link: https://syzkaller.appspot.com/bug?extid=3ed715090790806d8b18
compiler: clang version 9.0.0 (/home/glider/llvm/clang 80fee25776c2fb61e74c1ecb1a523375c2500b69)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=174ae381a00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1490948aa00000

The bug was bisected to:

commit b6da31b2c07c46f2dcad1d86caa835227a16d9ff
Author: DaeRyong Jeong <threeearcat@xxxxxxxxx>
Date: Mon Apr 30 15:27:04 2018 +0000

tty: Fix data race in tty_insert_flip_string_fixed_flag

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=146590e6a00000
final crash: https://syzkaller.appspot.com/x/report.txt?x=166590e6a00000
console output: https://syzkaller.appspot.com/x/log.txt?x=126590e6a00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+3ed715090790806d8b18@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: b6da31b2c07c ("tty: Fix data race in tty_insert_flip_string_fixed_flag")

======================================================
WARNING: possible circular locking dependency detected
5.2.0-rc5+ #3 Not tainted
------------------------------------------------------
syz-executor423/8208 is trying to acquire lock:
0000000094bc2798 (console_owner){-.-.}, at: console_lock_spinning_enable+0x31/0x60 kernel/printk/printk.c:1641

but task is already holding lock:
0000000007643134 (&(&port->lock)->rlock){-.-.}, at: pty_write+0xbd/0x190 drivers/tty/pty.c:120

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (&(&port->lock)->rlock){-.-.}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xa1/0xc0 kernel/locking/spinlock.c:159
tty_port_tty_get drivers/tty/tty_port.c:287 [inline]
tty_port_default_wakeup+0x20/0xa0 drivers/tty/tty_port.c:47
tty_port_tty_wakeup+0x5a/0x70 drivers/tty/tty_port.c:387
uart_write_wakeup+0x48/0x60 drivers/tty/serial/serial_core.c:103
serial8250_tx_chars+0x623/0x830 drivers/tty/serial/8250/8250_port.c:1806
serial8250_handle_irq+0x255/0x390 drivers/tty/serial/8250/8250_port.c:1879
serial8250_default_handle_irq+0xc5/0x1d0 drivers/tty/serial/8250/8250_port.c:1895
serial8250_interrupt+0xad/0x190 drivers/tty/serial/8250/8250_core.c:125
__handle_irq_event_percpu+0x113/0x560 kernel/irq/handle.c:149
handle_irq_event_percpu kernel/irq/handle.c:189 [inline]
handle_irq_event+0x10a/0x2f0 kernel/irq/handle.c:206
handle_edge_irq+0x29f/0xca0 kernel/irq/chip.c:822
generic_handle_irq_desc include/linux/irqdesc.h:156 [inline]
handle_irq+0x3e/0x50 arch/x86/kernel/irq_64.c:34
do_IRQ+0xc4/0x1a0 arch/x86/kernel/irq.c:247
ret_from_intr+0x0/0x1e
native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60
arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:571
default_idle_call kernel/sched/idle.c:94 [inline]
cpuidle_idle_call kernel/sched/idle.c:154 [inline]
do_idle+0x18a/0x760 kernel/sched/idle.c:263
cpu_startup_entry+0x25/0x30 kernel/sched/idle.c:354
start_secondary+0x425/0x4c0 arch/x86/kernel/smpboot.c:265
secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243

-> #1 (&port_lock_key){-.-.}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xa1/0xc0 kernel/locking/spinlock.c:159
serial8250_console_write+0x1d1/0xba0 drivers/tty/serial/8250/8250_port.c:3245
univ8250_console_write+0x50/0x70 drivers/tty/serial/8250/8250_core.c:586
call_console_drivers kernel/printk/printk.c:1779 [inline]
console_unlock+0x95f/0xf20 kernel/printk/printk.c:2463
vprintk_emit+0x239/0x3a0 kernel/printk/printk.c:1986
vprintk_default+0x28/0x30 kernel/printk/printk.c:2013
vprintk_func+0x158/0x170 kernel/printk/printk_safe.c:386
printk+0xc4/0x11d kernel/printk/printk.c:2046
register_console+0xa81/0xe30 kernel/printk/printk.c:2788
univ8250_console_init+0x4b/0x4d drivers/tty/serial/8250/8250_core.c:681
console_init+0x56/0x9c kernel/printk/printk.c:2874
start_kernel+0x49e/0x860 init/main.c:688
x86_64_start_reservations+0x18/0x2e arch/x86/kernel/head64.c:470
x86_64_start_kernel+0x7a/0x7d arch/x86/kernel/head64.c:451
secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243

-> #0 (console_owner){-.-.}:
lock_acquire+0x158/0x250 kernel/locking/lockdep.c:4303
console_lock_spinning_enable+0x56/0x60 kernel/printk/printk.c:1644
console_unlock+0x79f/0xf20 kernel/printk/printk.c:2460
vprintk_emit+0x239/0x3a0 kernel/printk/printk.c:1986
vprintk_default+0x28/0x30 kernel/printk/printk.c:2013
vprintk_func+0x158/0x170 kernel/printk/printk_safe.c:386
printk+0xc4/0x11d kernel/printk/printk.c:2046
fail_dump lib/fault-inject.c:45 [inline]
should_fail+0x5c5/0x860 lib/fault-inject.c:144
__should_failslab+0x11a/0x160 mm/failslab.c:32
should_failslab+0x9/0x20 mm/slab_common.c:1610
slab_pre_alloc_hook mm/slab.h:420 [inline]
slab_alloc mm/slab.c:3312 [inline]
__do_kmalloc mm/slab.c:3658 [inline]
__kmalloc+0x7a/0x310 mm/slab.c:3669
kmalloc include/linux/slab.h:552 [inline]
tty_buffer_alloc drivers/tty/tty_buffer.c:175 [inline]
__tty_buffer_request_room+0x1ef/0x560 drivers/tty/tty_buffer.c:273
tty_insert_flip_string_fixed_flag+0xa4/0x2b0 drivers/tty/tty_buffer.c:318
tty_insert_flip_string include/linux/tty_flip.h:37 [inline]
pty_write+0xe2/0x190 drivers/tty/pty.c:122
n_tty_write+0x5f5/0x12d0 drivers/tty/n_tty.c:2356
do_tty_write drivers/tty/tty_io.c:961 [inline]
tty_write+0x581/0x860 drivers/tty/tty_io.c:1045
__vfs_write+0xf9/0x7d0 fs/read_write.c:494
vfs_write+0x227/0x510 fs/read_write.c:558
ksys_write+0x16b/0x2a0 fs/read_write.c:611
__do_sys_write fs/read_write.c:623 [inline]
__se_sys_write fs/read_write.c:620 [inline]
__x64_sys_write+0x7b/0x90 fs/read_write.c:620
do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x49/0xbe

other info that might help us debug this:

Chain exists of:
console_owner --> &port_lock_key --> &(&port->lock)->rlock

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&(&port->lock)->rlock);
lock(&port_lock_key);
lock(&(&port->lock)->rlock);
lock(console_owner);

*** DEADLOCK ***

6 locks held by syz-executor423/8208:
#0: 00000000cef2c391 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272
#1: 00000000a7608faf (&tty->atomic_write_lock){+.+.}, at: tty_write_lock drivers/tty/tty_io.c:887 [inline]
#1: 00000000a7608faf (&tty->atomic_write_lock){+.+.}, at: do_tty_write drivers/tty/tty_io.c:910 [inline]
#1: 00000000a7608faf (&tty->atomic_write_lock){+.+.}, at: tty_write+0x21d/0x860 drivers/tty/tty_io.c:1045
#2: 00000000c1195898 (&tty->termios_rwsem){++++}, at: n_tty_write+0x22e/0x12d0 drivers/tty/n_tty.c:2316
#3: 00000000fc5a138e (&ldata->output_lock){+.+.}, at: n_tty_write+0x5a9/0x12d0 drivers/tty/n_tty.c:2355
#4: 0000000007643134 (&(&port->lock)->rlock){-.-.}, at: pty_write+0xbd/0x190 drivers/tty/pty.c:120
#5: 00000000a1673955 (console_lock){+.+.}, at: vprintk_emit+0x21c/0x3a0 kernel/printk/printk.c:1985

stack backtrace:
CPU: 1 PID: 8208 Comm: syz-executor423 Not tainted 5.2.0-rc5+ #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1d8/0x2f8 lib/dump_stack.c:113
print_circular_bug+0xd34/0xf20 kernel/locking/lockdep.c:1564
check_prev_add kernel/locking/lockdep.c:2310 [inline]
check_prevs_add kernel/locking/lockdep.c:2418 [inline]
validate_chain+0x59d0/0x84f0 kernel/locking/lockdep.c:2800
__lock_acquire+0xcf7/0x1a40 kernel/locking/lockdep.c:3793
lock_acquire+0x158/0x250 kernel/locking/lockdep.c:4303
console_lock_spinning_enable+0x56/0x60 kernel/printk/printk.c:1644
console_unlock+0x79f/0xf20 kernel/printk/printk.c:2460
vprintk_emit+0x239/0x3a0 kernel/printk/printk.c:1986
vprintk_default+0x28/0x30 kernel/printk/printk.c:2013
vprintk_func+0x158/0x170 kernel/printk/printk_safe.c:386
printk+0xc4/0x11d kernel/printk/printk.c:2046
fail_dump lib/fault-inject.c:45 [inline]
should_fail+0x5c5/0x860 lib/fault-inject.c:144
__should_failslab+0x11a/0x160 mm/failslab.c:32
should_failslab+0x9/0x20 mm/slab_common.c:1610
slab_pre_alloc_hook mm/slab.h:420 [inline]
slab_alloc mm/slab.c:3312 [inline]
__do_kmalloc mm/slab.c:3658 [inline]
__kmalloc+0x7a/0x310 mm/slab.c:3669
kmalloc include/linux/slab.h:552 [inline]
tty_buffer_alloc drivers/tty/tty_buffer.c:175 [inline]
__tty_buffer_request_room+0x1ef/0x560 drivers/tty/tty_buffer.c:273
tty_insert_flip_string_fixed_flag+0xa4/0x2b0 drivers/tty/tty_buffer.c:318
tty_insert_flip_string include/linux/tty_flip.h:37 [inline]
pty_write+0xe2/0x190 drivers/tty/pty.c:122
n_tty_write+0x5f5/0x12d0 drivers/tty/n_tty.c:2356
do_tty_write drivers/tty/tty_io.c:961 [inline]
tty_write+0x581/0x860 drivers/tty/tty_io.c:1045
__vfs_write+0xf9/0x7d0 fs/read_write.c:494
vfs_write+0x227/0x510 fs/read_write.c:558
ksys_write+0x16b/0x2a0 fs/read_write.c:611
__do_sys_write fs/read_write.c:623 [inline]
__se_sys_write fs/read_write.c:620 [inline]
__x64_sys_write+0x7b/0x90 fs/read_write.c:620
do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4404c9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 0f 83 5b 14 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffd67920e98 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007ffd67920ea0 RCX: 00000000004404c9
RDX: 00000000ffffff78 RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 0000000000000004 R08: 0000000000000001 R09: 00007ffd67920032
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401db0
R13: 0000000000401e40 R14: 0000000000000000 R15: 0000000000000000

---
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See https://goo.gl/tpsmEJ for more information about syzbot.
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syzbot will keep track of this bug report. See:
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

Next message: Jing Liu: "[PATCH RFC] kvm: x86: AVX512_BF16 feature support"
Previous message: Ulf Hansson: "[GIT PULL] MMC fixes for v5.2-rc6"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]