From 1cdb07d8946caa15f4b29534da745240c107892e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?C=C3=A1ssio=20Gabriel?= Date: Thu, 4 Jun 2026 21:31:06 -0400 Subject: [PATCH] ALSA: firewire-motu: Protect register DSP event queue positions MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit [ Upstream commit 98fb1c1bb11e29eb609b7200a25e136e05aa4498 ] 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: 634ec0b2906e ("ALSA: firewire-motu: notify event for parameter change in register DSP model") Cc: stable@vger.kernel.org Signed-off-by: Cássio Gabriel Reviewed-by: Takashi Sakamoto Signed-off-by: Takashi Iwai 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 Signed-off-by: Greg Kroah-Hartman --- .../motu/motu-register-dsp-message-parser.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/sound/firewire/motu/motu-register-dsp-message-parser.c b/sound/firewire/motu/motu-register-dsp-message-parser.c index ef3b0b0f0dab..abafae59f365 100644 --- a/sound/firewire/motu/motu-register-dsp-message-parser.c +++ b/sound/firewire/motu/motu-register-dsp-message-parser.c @@ -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; }