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 hda_codec_driver_probe/remove() found in
sound/pci/hda/hda_bind.c with their component->probe/remove() instead.

One of the reasons for that is the expectation of
snd_hda_codec_device_new() 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
snd_hda_codec_cleanup_for_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.

Suggested-by: Takashi Iwai <tiwai@suse.com>
Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://lore.kernel.org/r/20230119143235.1159814-1-cezary.rojewski@intel.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/pci/hda/hda_bind.c b/sound/pci/hda/hda_bind.c
index 1a868dd..890c2f7 100644 (file)
--- a/sound/pci/hda/hda_bind.c
+++ b/sound/pci/hda/hda_bind.c
@@ -144,6 +144,7 @@ static int hda_codec_driver_probe(struct device *dev)
 
  error:
        snd_hda_codec_cleanup_for_unbind(codec);
+       codec->preset = NULL;
        return err;
 }
 
@@ -166,6 +167,7 @@ static int hda_codec_driver_remove(struct device *dev)
        if (codec->patch_ops.free)
                codec->patch_ops.free(codec);
        snd_hda_codec_cleanup_for_unbind(codec);
+       codec->preset = NULL;
        module_put(dev->driver->owner);
        return 0;
 }

diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
index edd653e..ac1cc7c 100644 (file)
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -795,7 +795,6 @@ void snd_hda_codec_cleanup_for_unbind(struct hda_codec *codec)
        snd_array_free(&codec->cvt_setups);
        snd_array_free(&codec->spdif_out);
        snd_array_free(&codec->verbs);
-       codec->preset = NULL;
        codec->follower_dig_outs = NULL;
        codec->spdif_status_reset = 0;
        snd_array_free(&codec->mixers);