From 98fb1c1bb11e29eb609b7200a25e136e05aa4498 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?C=C3=A1ssio=20Gabriel?= Date: Thu, 21 May 2026 08:01:23 -0300 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 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 --- .../firewire/motu/motu-register-dsp-message-parser.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/sound/firewire/motu/motu-register-dsp-message-parser.c b/sound/firewire/motu/motu-register-dsp-message-parser.c index a8053e3ef065..4ec23e6880d9 100644 --- a/sound/firewire/motu/motu-register-dsp-message-parser.c +++ b/sound/firewire/motu/motu-register-dsp-message-parser.c @@ -386,6 +386,8 @@ 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 @@ -395,13 +397,14 @@ 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; - - if (pos == parser->push_pos) - return false; + unsigned int pos; guard(spinlock_irqsave)(&parser->lock); + if (parser->pull_pos == parser->push_pos) + return false; + + pos = parser->pull_pos; *event = parser->event_queue[pos]; ++pos;