Commit 80bb50e2 authored by Berk Cem Goksel's avatar Berk Cem Goksel Committed by Takashi Iwai
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ALSA: caiaq: take a reference on the USB device in create_card() 



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: b04dcbb7 ("ALSA: caiaq: Use snd_card_free_when_closed() at disconnection")
Cc: stable@vger.kernel.org
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Signed-off-by: default avatarBerk Cem Goksel <berkcgoksel@gmail.com>
Link: https://patch.msgid.link/20260413034941.1131465-3-berkcgoksel@gmail.com


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent f365e47b

sound/usb/caiaq/device.c

+2 −2
Original line number Diff line number Diff line
@@ -384,7 +384,7 @@ 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,
@@ -410,7 +410,7 @@ 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));