ALSA: hda: Fix null-ptr-deref when i915 fails and hdmi is denylisted

If snd_hda_hdmi_codec module is denylisted and any event causes i915
enumeration to fail, is_likely_hdmi_codec() ends in null-ptr-deref.

As snd_soc_hda is an ASoC-based driver, its initialization is delayed
until all the necessary components appear in the system - allowing
actual sound card to enumerate. snd_hda_codec_configure() gets called by
the avs-driver core during probe_codecs() but the
snd_hda_codec_device_new(), necessary to complete codecs initialization,
happens only when codec-component of hda sound card is being probed.

Denylisting snd_hda_codec_hdmi module causes snd_hda_codec_configure()
to reach: codec_bind_generic() -> is_likely_hdmi_codec() which makes use
of ->wcaps and at this point the it isn't initialized yet - again,
requires completion of snd_hda_codec_device_new().

Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://lore.kernel.org/r/20220706120230.427296-3-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 c572fb5886d5d63f56ead62ab2d5e5e192d75245..cae9a975cbcca809bdd59993e1343eebd4c6ad76 100644 (file)
--- a/sound/pci/hda/hda_bind.c
+++ b/sound/pci/hda/hda_bind.c
@@ -248,6 +248,13 @@ static bool is_likely_hdmi_codec(struct hda_codec *codec)
 {
        hda_nid_t nid;
 
+       /*
+        * For ASoC users, if snd_hda_hdmi_codec module is denylisted and any
+        * event causes i915 enumeration to fail, ->wcaps remains uninitialized.
+        */
+       if (!codec->wcaps)
+               return true;
+
        for_each_hda_codec_node(nid, codec) {
                unsigned int wcaps = get_wcaps(codec, nid);
                switch (get_wcaps_type(wcaps)) {