[PATCH 1/2] ALSA: caiaq: fix use-after-free and double-free in setup_card()

[Berk Cem Goksel <berkcgoksel@gmail.com>]

When snd_card_register() fails in setup_card(), snd_card_free() is
called on the card, but there is no return statement afterwards.
Execution falls through to snd_usb_caiaq_control_init(cdev), which
dereferences members of the just-freed card, resulting in a
use-after-free.

setup_card() is void and init_card() still returns 0 on this path,
so snd_probe() leaves the freed card pointer in the USB interface's
private data via usb_set_intfdata(). When the device is later
disconnected, snd_usb_caiaq_disconnect() calls
snd_card_free_when_closed() on that same pointer, producing a
double-free and slab corruption.

Add the missing return so a failed snd_card_register() cleanly
aborts setup without touching freed memory.

The issue is reachable by any caiaq-compatible USB device whose
descriptors cause snd_card_register() to fail. It was reproduced
with raw-gadget + dummy_hcd on 7.0.0-rc5 (arm64, KASAN).

Fixes: 523f1dce7096 ("ALSA: snd-usb-caiaq: add support for NI Audio Kontrol 1")
Cc: stable@vger.kernel.org
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Signed-off-by: Berk Cem Goksel <berkcgoksel@gmail.com>
---
 sound/usb/caiaq/device.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sound/usb/caiaq/device.c b/sound/usb/caiaq/device.c
--- a/sound/usb/caiaq/device.c
+++ b/sound/usb/caiaq/device.c
@@ -369,6 +369,7 @@
 	if (ret < 0) {
 		dev_err(dev, "snd_card_register() returned %d\n", ret);
 		snd_card_free(cdev->chip.card);
+		return;
 	}

 	ret = snd_usb_caiaq_control_init(cdev);