From 7a5f1cd22d47f8ca4b760b6334378ae42c1bd24b Mon Sep 17 00:00:00 2001 From: Deepanshu Kartikey Date: Sun, 26 Apr 2026 05:49:34 +0530 Subject: ALSA: caiaq: fix usb_dev refcount leak on probe failure 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(). Fixes: 80bb50e2d459 ("ALSA: caiaq: take a reference on the USB device in create_card()") 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 Link: https://patch.msgid.link/20260426001934.70813-1-kartikey406@gmail.com Signed-off-by: Takashi Iwai --- 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; -- cgit v1.2.3