CVE-2023-52736

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

ALSA: hda: Do not unset preset when cleaning up codec

Several functions that take part in codec's initialization and removal are re-used by ASoC codec drivers implementations. Drivers mimic the behavior of hdacodecdriverprobe/remove() found in sound/pci/hda/hdabind.c with their component->probe/remove() instead.

One of the reasons for that is the expectation of sndhdacodecdevicenew() to receive a valid pointer to an instance of struct snd_card. This expectation can be met only once sound card components probing commences.

As ASoC sound card may be unbound without codec device being actually removed from the system, unsetting ->preset in sndhdacodeccleanupfor_unbind() interferes with module unload -> load scenario causing null-ptr-deref. Preset is assigned only once, during device/driver matching whereas ASoC codec driver's module reloading may occur several times throughout the lifetime of an audio stack.