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ALSA: firewire-motu: Protect register DSP event queue positions

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[ Upstream commit 98fb1c1bb1 ]

The register DSP event queue is updated under parser->lock, but
snd_motu_register_dsp_message_parser_count_event() reads pull_pos and
push_pos without the lock.
snd_motu_register_dsp_message_parser_copy_event() also reads both queue
positions before taking the lock.

Protect these accesses with parser->lock as well. This keeps the hwdep
poll/read path consistent with the producer side and with the cached
meter/parameter accessors.

Fixes: 634ec0b290 ("ALSA: firewire-motu: notify event for parameter change in register DSP model")
Cc: stable@vger.kernel.org
Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20260521-alsa-firewire-motu-event-locking-v1-1-708e1c2b5e56@gmail.com
[ converted copy_event() from manual spin_lock_irqsave/spin_unlock_irqrestore to guard(spinlock_irqsave) ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Cássio Gabriel
2026-06-19 13:39:41 +02:00
committed by Greg Kroah-Hartman
parent b3f4f82d13
commit 1cdb07d894
1 changed files with 7 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files
sound/firewire/motu/motu-register-dsp-message-parser.c
+7 -7
View File
@@ -393,6 +393,8 @@ unsigned int snd_motu_register_dsp_message_parser_count_event(struct snd_motu *m
{
struct msg_parser *parser = motu->message_parser;
guard(spinlock_irqsave)(&parser->lock);
if (parser->pull_pos > parser->push_pos)
return EVENT_QUEUE_SIZE - parser->pull_pos + parser->push_pos;
else
@@ -402,14 +404,14 @@ unsigned int snd_motu_register_dsp_message_parser_count_event(struct snd_motu *m
bool snd_motu_register_dsp_message_parser_copy_event(struct snd_motu *motu, u32 *event)
{
struct msg_parser *parser = motu->message_parser;
unsigned int pos = parser->pull_pos;
unsigned long flags;
unsigned int pos;
if (pos == parser->push_pos)
guard(spinlock_irqsave)(&parser->lock);
if (parser->pull_pos == parser->push_pos)
return false;
spin_lock_irqsave(&parser->lock, flags);
pos = parser->pull_pos;
*event = parser->event_queue[pos];
++pos;
@@ -417,7 +419,5 @@ bool snd_motu_register_dsp_message_parser_copy_event(struct snd_motu *motu, u32
pos = 0;
parser->pull_pos = pos;
spin_unlock_irqrestore(&parser->lock, flags);
return true;
}