Commit 7a5f1cd2 authored by Deepanshu Kartikey's avatar Deepanshu Kartikey Committed by Takashi Iwai
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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: 80bb50e2 ("ALSA: caiaq: take a reference on the USB device in create_card()")
Reported-by: default avatar <syzbot+2afd7e71155c7e241560@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=2afd7e71155c7e241560


Tested-by: default avatar <syzbot+2afd7e71155c7e241560@syzkaller.appspotmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarDeepanshu Kartikey <kartikey406@gmail.com>
Link: https://patch.msgid.link/20260426001934.70813-1-kartikey406@gmail.com


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent d1f73f16

sound/usb/caiaq/device.c

+1 −1
Original line number Diff line number Diff line
@@ -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;