[PATCH 6.12 30/35] ALSA: caiaq: take a reference on the USB device in create_card()

Greg Kroah-Hartman
2026-04-24T13:44:21Z

From: Berk Cem Goksel <berkcgoksel@gmail.com>

commit 80bb50e2d459213cccff3111d5ef98ed4238c0d5 upstream.

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 <andreyknvl@gmail.com>
Signed-off-by: Berk Cem Goksel <berkcgoksel@gmail.com>
Link: https://patch.msgid.link/20260413034941.1131465-3-berkcgoksel@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
sound/usb/caiaq/device.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/sound/usb/caiaq/device.c
+++ b/sound/usb/caiaq/device.c
@@ -384,7 +384,7 @@ static void card_free(struct snd_card *c
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
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));