linux/sound/core/seq
Takashi Iwai 7f0973e973 ALSA: seq: Fix lockdep warnings due to double mutex locks
The port subscription code uses double mutex locks for source and
destination ports, and this may become racy once when wrongly set up.
It leads to lockdep warning splat, typically triggered by fuzzer like
syzkaller, although the actual deadlock hasn't been seen, so far.

This patch simplifies the handling by reducing to two single locks, so
that no lockdep warning will be trigger any longer.

By splitting to two actions, a still-in-progress element shall be
added in one list while handling another.  For ignoring this element,
a new check is added in deliver_to_subscribers().

Along with it, the code to add/remove the subscribers list element was
cleaned up and refactored.

BugLink: http://lkml.kernel.org/r/CACT4Y+aKQXV7xkBW9hpQbzaDO7LrUvohxWh-UwMxXjDy-yBD=A@mail.gmail.com
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2016-02-03 14:51:51 +01:00
..
oss ALSA: seq: Degrade the error message for too many opens 2016-01-25 11:52:23 +01:00
Kconfig ALSA: clean up the logic for building sequencer modules 2009-05-29 11:49:42 +02:00
Makefile ALSA: core: Fix randconfig build wrt CONFIG_PROC_FS 2015-05-29 07:21:02 +02:00
seq_clientmgr.c ALSA: seq: Fix lockdep warnings due to double mutex locks 2016-02-03 14:51:51 +01:00
seq_clientmgr.h [ALSA] sound/core/seq: move declarations of globally visible variables to proper headers 2008-01-31 17:29:35 +01:00
seq_compat.c ALSA: seq: Fix snd_seq_call_port_info_ioctl in compat mode 2016-01-18 14:39:13 +01:00
seq_device.c ALSA: core: Fix randconfig build wrt CONFIG_PROC_FS 2015-05-29 07:21:02 +02:00
seq_dummy.c ALSA: seq: Drop snd_seq_autoload_lock() and _unlock() 2015-02-12 14:42:31 +01:00
seq_fifo.c ALSA: seq: Drop superfluous error/debug messages after malloc failures 2015-03-10 15:41:18 +01:00
seq_fifo.h [ALSA] Remove xxx_t typedefs: Sequencer 2006-01-03 12:17:52 +01:00
seq_info.c ALSA: core: Build conditionally and remove superfluous ifdefs 2015-04-24 17:31:07 +02:00
seq_info.h ALSA: replace CONFIG_PROC_FS with CONFIG_SND_PROC_FS 2015-05-27 21:25:19 +02:00
seq_lock.c ALSA: seq: Use standard printk helpers 2014-02-14 08:14:18 +01:00
seq_lock.h
seq_memory.c ALSA: seq: Drop superfluous error/debug messages after malloc failures 2015-03-10 15:41:18 +01:00
seq_memory.h ALSA: core: sparse cleanups 2011-02-14 17:10:11 +01:00
seq_midi_emul.c ALSA: seq: potential out of bounds in do_control() 2015-02-12 11:07:48 +01:00
seq_midi_event.c sound: Add module.h to the previously silent sound users 2011-10-31 19:31:21 -04:00
seq_midi.c ALSA: seq: Drop snd_seq_autoload_lock() and _unlock() 2015-02-12 14:42:31 +01:00
seq_ports.c ALSA: seq: Fix lockdep warnings due to double mutex locks 2016-02-03 14:51:51 +01:00
seq_ports.h ALSA: seq: remove unused callback_all field 2015-01-26 13:56:58 +01:00
seq_prioq.c ALSA: seq: Drop superfluous error/debug messages after malloc failures 2015-03-10 15:41:18 +01:00
seq_prioq.h [ALSA] Remove xxx_t typedefs: Sequencer 2006-01-03 12:17:52 +01:00
seq_queue.c ALSA: seq: Fix race at timer setup and close 2016-01-12 17:50:41 +01:00
seq_queue.h [ALSA] semaphore -> mutex (core part) 2006-03-22 10:24:50 +01:00
seq_system.c sound: Add export.h for THIS_MODULE/EXPORT_SYMBOL where needed 2011-10-31 19:31:22 -04:00
seq_system.h [ALSA] Remove xxx_t typedefs: Sequencer 2006-01-03 12:17:52 +01:00
seq_timer.c ALSA: seq: Fix yet another races among ALSA timer accesses 2016-02-01 12:23:29 +01:00
seq_timer.h [ALSA] sound/core/seq: move declarations of globally visible variables to proper headers 2008-01-31 17:29:35 +01:00
seq_virmidi.c ALSA: rawmidi: Make snd_rawmidi_transmit() race-free 2016-02-03 14:51:28 +01:00
seq.c Subject: ALSA: seq: Remove autoload locks in driver registration 2014-10-18 20:25:19 +02:00