In the Linux kernel, the following vulnerability has been resolved: ALSA: caiaq: Handle probe...

In the Linux kernel, the following vulnerability has been resolved:

ALSA: caiaq: Handle probe errors properly

The probe procedure of setup_card() in caiaq driver doesn't treat the error cases gracefully, e.g. the error from snd_card_register() calls snd_card_free() but continues. This would lead to a UAF for the further calls like snd_usb_caiaq_control_init(), as Berk suggested in another patch in the link below.

However, the problem is not only that; in general, this function drops the all error handlings (as it's a void function) although its caller can propagate an error to snd_probe(), which eventually calls snd_card_free() as a proper error path. That said, we should treat each error case in setup_card(), and just return the error code promptly, which is then handled later as a fatal error in snd_probe().

This patch achieves it by changing the setup_card() to return an error code. Also, the superfluous snd_card_free() call is removed, too.

Note that card->private_free can be set still safely at returning an error. All called functions in card_free() have checks of the unassigned resources or NULL checks.