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([2405:201:682f:383f:421f:2607:ad77:4337]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3613fae178fsm10212835a91.7.2026.04.25.17.19.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 25 Apr 2026 17:19:41 -0700 (PDT) From: Deepanshu Kartikey To: zonque@gmail.com, perex@perex.cz, tiwai@suse.com Cc: linux-sound@vger.kernel.org, linux-kernel@vger.kernel.org, Deepanshu Kartikey , syzbot+2afd7e71155c7e241560@syzkaller.appspotmail.com, stable@vger.kernel.org Subject: [PATCH] ALSA: caiaq: fix usb_dev refcount leak on probe failure Date: Sun, 26 Apr 2026 05:49:34 +0530 Message-ID: <20260426001934.70813-1-kartikey406@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit create_card() takes a reference on the USB device with usb_get_dev() and stores the matching usb_put_dev() in card_free(), which is installed as the snd_card's ->private_free destructor. However, ->private_free is only assigned near the end of init_card(), after several failure points (usb_set_interface(), EP type checks, usb_submit_urb(), the EP1_CMD_GET_DEVICE_INFO exchange, and its timeout). When any of those fail, init_card() returns an error to snd_probe(), which calls snd_card_free(card). Because ->private_free is still NULL, card_free() never runs, the usb_get_dev() reference is not dropped, and the struct usb_device leaks along with its descriptor allocations and device_private. syzbot reproduces this with a malformed UAC3 device whose only valid altsetting is 0; init_card()'s usb_set_interface(usb_dev, 0, 1) call fails with -EIO and triggers the leak. Move the ->private_free assignment into create_card(), immediately after usb_get_dev(), so that every error path reaching snd_card_free() balances the reference. card_free()'s callees (snd_usb_caiaq_input_free, free_urbs, kfree) already tolerate the partially-initialized state because the chip private area is zero-initialized by snd_card_new(). Reported-by: syzbot+2afd7e71155c7e241560@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=2afd7e71155c7e241560 Tested-by: syzbot+2afd7e71155c7e241560@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Signed-off-by: Deepanshu Kartikey --- sound/usb/caiaq/device.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sound/usb/caiaq/device.c b/sound/usb/caiaq/device.c index 8af0c04041ee..ad9f744b496b 100644 --- a/sound/usb/caiaq/device.c +++ b/sound/usb/caiaq/device.c @@ -423,6 +423,7 @@ static int create_card(struct usb_device *usb_dev, cdev = caiaqdev(card); cdev->chip.dev = usb_get_dev(usb_dev); + card->private_free = card_free; cdev->chip.card = card; cdev->chip.usb_id = USB_ID(le16_to_cpu(usb_dev->descriptor.idVendor), le16_to_cpu(usb_dev->descriptor.idProduct)); @@ -511,7 +512,6 @@ static int init_card(struct snd_usb_caiaqdev *cdev) scnprintf(card->longname, sizeof(card->longname), "%s %s (%s)", cdev->vendor_name, cdev->product_name, usbpath); - card->private_free = card_free; err = setup_card(cdev); if (err < 0) return err; -- 2.43.0