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Fri, 06 Nov 2026 10:09:39 -0800 (PST) Received: from localhost.localdomain ([103.177.253.113]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-1b25e4a5628sm8366464c88.10.2026.11.06.10.09.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 06 Nov 2026 10:09:39 -0800 (PST) From: Sreeraj S Kurup To: perex@perex.cz, tiwai@suse.com, tiwai@suse.de Cc: linux-kernel@vger.kernel.org, linux-sound@vger.kernel.org, Sreeraj S Kurup Subject: [PATCH] ALSA: control: Synchronize LED mode accesses Date: Fri, 6 Nov 2026 18:08:12 +0000 Message-ID: <20261106180812.5097-1-sreekuttan2156239@gmail.com> X-Mailer: git-send-email 2.55.0 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit mode_store() updates led->mode while holding snd_ctl_led_mutex. However, snd_ctl_led_set_state() and mode_show() read this field without holding the same mutex. This can cause a data race when userspace changes the mode while another path reads it. Read the mode under snd_ctl_led_mutex in snd_ctl_led_set_state() and use the local value after releasing the mutex. Also protect the mode read in mode_show() with the mutex. Signed-off-by: Sreeraj S Kurup --- sound/core/control_led.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/sound/core/control_led.c b/sound/core/control_led.c index 501387287ae6..044430b2f1a2 100644 --- a/sound/core/control_led.c +++ b/sound/core/control_led.c @@ -140,6 +140,7 @@ static void snd_ctl_led_set_state(struct snd_card *card, unsigned int access, { struct snd_ctl_led *led; struct snd_ctl_led_ctl *lctl; + enum snd_ctl_led_mode mode; int route; bool found; @@ -168,8 +169,9 @@ static void snd_ctl_led_set_state(struct snd_card *card, unsigned int access, UPDATE_ROUTE(route, snd_ctl_led_get(lctl)); } } + mode = led->mode; } - switch (led->mode) { + switch (mode) { case MODE_OFF: route = 1; break; case MODE_ON: route = 0; break; case MODE_FOLLOW_ROUTE: if (route >= 0) route ^= 1; break; @@ -382,6 +384,8 @@ static ssize_t mode_show(struct device *dev, struct snd_ctl_led *led = container_of(dev, struct snd_ctl_led, dev); const char *str = NULL; + guard(mutex)(&snd_ctl_led_mutex); + switch (led->mode) { case MODE_FOLLOW_MUTE: str = "follow-mute"; break; case MODE_FOLLOW_ROUTE: str = "follow-route"; break; -- 2.55.0