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[177.4.162.74]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-304432dc579sm219449eec.6.2026.05.21.04.01.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 May 2026 04:01:28 -0700 (PDT) From: =?utf-8?q?C=C3=A1ssio_Gabriel?= Date: Thu, 21 May 2026 08:01:23 -0300 Subject: [PATCH] ALSA: firewire-motu: Protect register DSP event queue positions Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260521-alsa-firewire-motu-event-locking-v1-1-708e1c2b5e56@gmail.com> X-B4-Tracking: v=1; b=H4sIAAAAAAAC/yXNQQ6CMBCF4auQWTtJ24QSvAphUcqAo9iaTkETw t2tsniLb/O/HYQSk8C12iHRxsIxFOhLBf7mwkzIYzEYZayqlUa3iMOJE73L8BnzirRRyLhE/+A w46jrdmht46zxUDKvRBN//hddf1rW4U4+/7pwHF8pnXkvhAAAAA== X-Change-ID: 20260501-alsa-firewire-motu-event-locking-d159b967a62c To: Takashi Sakamoto , Clemens Ladisch , Takashi Iwai , Jaroslav Kysela Cc: linux-sound@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, =?utf-8?q?C=C3=A1ssio_Gabriel?= X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=2150; i=cassiogabrielcontato@gmail.com; h=from:subject:message-id; bh=x7eWhfGu3dQUgHL1BW3vucHVFwNpD0MaxyrtevC/hYw=; b=owGbwMvMwCV2IdZeKur/u2bG02pJDFl8z9h+RGfvmK098dEEhcgPPGxMny+5XNIqeJdiHqqwT 8OR4VZPRykLgxgXg6yYIsvqpEWWe7oeXK2PW+EBM4eVCWQIAxenAEykqImR4bP0/Wdvow89iJ32 eYu8m9T57KKLJZlqX59q6MlMEXy014eR4Uvc537jHOGIbfYveWOuelQXZbgLpwXYruiRE1vd37W CAwA= X-Developer-Key: i=cassiogabrielcontato@gmail.com; a=openpgp; fpr=AB62A239BC8AE0D57F5EA848D05D3F1A5AFFEE83 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 chang= e in register DSP model") Cc: stable@vger.kernel.org Signed-off-by: C=C3=A1ssio Gabriel Reviewed-by: Takashi Sakamoto --- sound/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 =3D motu->message_parser; =20 + 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_cou= nt_event(struct snd_motu *m bool snd_motu_register_dsp_message_parser_copy_event(struct snd_motu *motu= , u32 *event) { struct msg_parser *parser =3D motu->message_parser; - unsigned int pos =3D parser->pull_pos; - - if (pos =3D=3D parser->push_pos) - return false; + unsigned int pos; =20 guard(spinlock_irqsave)(&parser->lock); =20 + if (parser->pull_pos =3D=3D parser->push_pos) + return false; + + pos =3D parser->pull_pos; *event =3D parser->event_queue[pos]; =20 ++pos; --- base-commit: 38c607c673155d6335591cdbd9c785fb2b7550e5 change-id: 20260501-alsa-firewire-motu-event-locking-d159b967a62c Best regards, -- =20 C=C3=A1ssio Gabriel