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Sun, 12 Apr 2026 20:50:36 -0700 (PDT) Received: from localhost.localdomain ([2405:6580:9cc0:8700:96ae:8c3d:9c98:97d9]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-35e4e2dbf47sm7030644a91.0.2026.04.12.20.50.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 12 Apr 2026 20:50:36 -0700 (PDT) From: Berk Cem Goksel To: zonque@gmail.com, tiwai@suse.com, perex@perex.cz Cc: linux-sound@vger.kernel.org, linux-kernel@vger.kernel.org, andreyknvl@gmail.com, stable@vger.kernel.org, Berk Cem Goksel Subject: [PATCH v2 2/2] ALSA: caiaq: take a reference on the USB device in create_card() Date: Mon, 13 Apr 2026 06:49:41 +0300 Message-Id: <20260413034941.1131465-3-berkcgoksel@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260413034941.1131465-1-berkcgoksel@gmail.com> References: <20260413034941.1131465-1-berkcgoksel@gmail.com> Precedence: bulk X-Mailing-List: linux-sound@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The caiaq driver stores a pointer to the parent USB device in cdev->chip.dev but never takes a reference on it. The card's private_free callback, snd_usb_caiaq_card_free(), can run asynchronously via snd_card_free_when_closed() after the USB device has already been disconnected and freed, so any access to cdev->chip.dev in that path dereferences a freed usb_device. On top of the refcounting issue, the current card_free implementation calls usb_reset_device(cdev->chip.dev). A reset in a free callback is inappropriate: the device is going away, the call takes the device lock in a teardown context, and the reset races with the disconnect path that the callback is already cleaning up after. Take a reference on the USB device in create_card() with usb_get_dev(), drop it with usb_put_dev() in the free callback, and remove the usb_reset_device() call. Fixes: b04dcbb7f7b1 ("ALSA: caiaq: Use snd_card_free_when_closed() at disconnection") Cc: stable@vger.kernel.org Cc: Andrey Konovalov Signed-off-by: Berk Cem Goksel --- v2: - Correct "Fixes:" tag - Remove null check before the usb_put_dev() call in card_free() sound/usb/caiaq/device.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/sound/usb/caiaq/device.c b/sound/usb/caiaq/device.c index d52f3b9a2bac..fa734fa61052 100644 --- a/sound/usb/caiaq/device.c +++ b/sound/usb/caiaq/device.c @@ -385,7 +385,7 @@ static void card_free(struct snd_card *card) snd_usb_caiaq_input_free(cdev); #endif snd_usb_caiaq_audio_free(cdev); - usb_reset_device(cdev->chip.dev); + usb_put_dev(cdev->chip.dev); } static int create_card(struct usb_device *usb_dev, @@ -411,7 +411,7 @@ static int create_card(struct usb_device *usb_dev, return err; cdev = caiaqdev(card); - cdev->chip.dev = usb_dev; + cdev->chip.dev = usb_get_dev(usb_dev); cdev->chip.card = card; cdev->chip.usb_id = USB_ID(le16_to_cpu(usb_dev->descriptor.idVendor), le16_to_cpu(usb_dev->descriptor.idProduct)); -- 2.34.1