ALSA: pcm: Free chmap at PCM free callback, too

commit a8ff48cb upstream.

The chmap ctls assigned to PCM streams are freed in the PCM disconnect
callback.  However, since the disconnect callback isn't called when
the card gets freed before registering, the chmap ctls may still be
left assigned.  They are eventually freed together with other ctls,
but it may cause an Oops at pcm_chmap_ctl_private_free(), as the
function refers to the assigned PCM stream, while the PCM objects have
been already freed beforehand.

The fix is to free the chmap ctls also at PCM free callback, not only
at PCM disconnect.
Reported-by: Laxminath Kasam <b_lkasam@codeaurora.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

sound/core/pcm.c

@@ -806,6 +806,14 @@ int snd_pcm_new_internal(struct snd_card *card, const char *id, int device,
 }
 EXPORT_SYMBOL(snd_pcm_new_internal);
 
+static void free_chmap(struct snd_pcm_str *pstr)
+{
+	if (pstr->chmap_kctl) {
+		snd_ctl_remove(pstr->pcm->card, pstr->chmap_kctl);
+		pstr->chmap_kctl = NULL;
+	}
+}
+
 static void snd_pcm_free_stream(struct snd_pcm_str * pstr)
 {
 	struct snd_pcm_substream *substream, *substream_next;
@@ -828,6 +836,7 @@ static void snd_pcm_free_stream(struct snd_pcm_str * pstr)
 		kfree(setup);
 	}
 #endif
+	free_chmap(pstr);
 }
 
 static int snd_pcm_free(struct snd_pcm *pcm)
@@ -1142,10 +1151,7 @@ static int snd_pcm_dev_disconnect(struct snd_device *device)
 			break;
 		}
 		snd_unregister_device(devtype, pcm->card, pcm->device);
-		if (pcm->streams[cidx].chmap_kctl) {
-			snd_ctl_remove(pcm->card, pcm->streams[cidx].chmap_kctl);
-			pcm->streams[cidx].chmap_kctl = NULL;
-		}
+		free_chmap(&pcm->streams[cidx]);
 	}
 	mutex_unlock(&pcm->open_mutex);
  unlock: