linux-stable/sound/core/seq
Takashi Iwai 97367c9722 ALSA: seq: Fix racy deletion of subscriber
It turned out that the current implementation of the port subscription
is racy.  The subscription contains two linked lists, and we have to
add to or delete from both lists.  Since both connection and
disconnection procedures perform the same order for those two lists
(i.e. src list, then dest list), when a deletion happens during a
connection procedure, the src list may be deleted before the dest list
addition completes, and this may lead to a use-after-free or an Oops,
even though the access to both lists are protected via mutex.

The simple workaround for this race is to change the access order for
the disconnection, namely, dest list, then src list.  This assures
that the connection has been established when disconnecting, and also
the concurrent deletion can be avoided.

Reported-and-tested-by: folkert <folkert@vanheusden.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210801182754.GP890690@belle.intranet.vanheusden.com
Link: https://lore.kernel.org/r/20210803114312.2536-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2021-08-03 13:43:40 +02:00
..
oss ALSA: seq: oss: Fix error check at system port creation 2021-06-17 16:02:26 +02:00
Kconfig treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
seq.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
seq_clientmgr.c ALSA: seq: Fix assignment in if condition 2021-06-09 17:30:26 +02:00
seq_clientmgr.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
seq_compat.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
seq_dummy.c ALSA: seq: Fix assignment in if condition 2021-06-09 17:30:26 +02:00
seq_fifo.c ALSA: seq: Fix assignment in if condition 2021-06-09 17:30:26 +02:00
seq_fifo.h ALSA: seq: Fix potential concurrent access to the deleted pool 2019-08-25 09:31:10 +02:00
seq_info.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
seq_info.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
seq_lock.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
seq_lock.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
seq_memory.c ALSA: seq: Fix assignment in if condition 2021-06-09 17:30:26 +02:00
seq_memory.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
seq_midi.c ALSA: seq: Fix assignment in if condition 2021-06-09 17:30:26 +02:00
seq_midi_emul.c ALSA: Use fallthrough pseudo-keyword 2020-07-09 13:01:29 +02:00
seq_midi_event.c ALSA: seq: More constifications 2020-01-05 16:14:29 +01:00
seq_ports.c ALSA: seq: Fix racy deletion of subscriber 2021-08-03 13:43:40 +02:00
seq_ports.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
seq_prioq.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
seq_prioq.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
seq_queue.c ALSA: seq: Fix assignment in if condition 2021-06-09 17:30:26 +02:00
seq_queue.h ALSA: seq: Use bool for snd_seq_queue internal flags 2020-12-06 09:35:53 +01:00
seq_system.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
seq_system.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
seq_timer.c ALSA: seq: Fix race of snd_seq_timer_open() 2021-06-10 17:21:30 +02:00
seq_timer.h ALSA: seq: Fix concurrent access to queue current tick/time 2020-02-14 15:53:09 +01:00
seq_virmidi.c ALSA: seq: Fix assignment in if condition 2021-06-09 17:30:26 +02:00