ALSA: hda - Fix possible races of accesses to connection list array

Like the previous fixes for cache hash accesses, a protection over
accesses to the widget connection list array must be provided.
Together with this action, remove snd_hda_get_conn_list() which can be
always race, and replace it with either snd_hda_get_num_conns() or
snd_hda_get_connections() calls.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/hda_codec.c

@@ -334,54 +334,23 @@ static hda_nid_t *lookup_conn_list(struct snd_array *array, hda_nid_t nid)
 	return NULL;
 }
 
-/**
- * snd_hda_get_conn_list - get connection list
- * @codec: the HDA codec
- * @nid: NID to parse
- * @listp: the pointer to store NID list
- *
- * Parses the connection list of the given widget and stores the list
- * of NIDs.
- *
- * Returns the number of connections, or a negative error code.
- */
-int snd_hda_get_conn_list(struct hda_codec *codec, hda_nid_t nid,
-			  const hda_nid_t **listp)
+/* read the connection and add to the cache */
+static int read_and_add_raw_conns(struct hda_codec *codec, hda_nid_t nid)
 {
-	struct snd_array *array = &codec->conn_lists;
-	int len, err;
 	hda_nid_t list[HDA_MAX_CONNECTIONS];
-	hda_nid_t *p;
-	bool added = false;
+	int len;
 
- again:
-	/* if the connection-list is already cached, read it */
-	p = lookup_conn_list(array, nid);
-	if (p) {
-		if (listp)
-			*listp = p + 2;
-		return p[1];
-	}
-	if (snd_BUG_ON(added))
-		return -EINVAL;
-
-	/* read the connection and add to the cache */
-	len = snd_hda_get_raw_connections(codec, nid, list, HDA_MAX_CONNECTIONS);
+	len = snd_hda_get_raw_connections(codec, nid, list, ARRAY_SIZE(list));
 	if (len < 0)
 		return len;
-	err = snd_hda_override_conn_list(codec, nid, len, list);
-	if (err < 0)
-		return err;
-	added = true;
-	goto again;
+	return snd_hda_override_conn_list(codec, nid, len, list);
 }
-EXPORT_SYMBOL_HDA(snd_hda_get_conn_list);
 
 /**
  * snd_hda_get_connections - copy connection list
  * @codec: the HDA codec
  * @nid: NID to parse
- * @conn_list: connection list array
+ * @conn_list: connection list array; when NULL, checks only the size
  * @max_conns: max. number of connections to store
  *
  * Parses the connection list of the given widget and stores the list
@@ -392,19 +361,39 @@ EXPORT_SYMBOL_HDA(snd_hda_get_conn_list);
 int snd_hda_get_connections(struct hda_codec *codec, hda_nid_t nid,
 			    hda_nid_t *conn_list, int max_conns)
 {
-	const hda_nid_t *list;
-	int len = snd_hda_get_conn_list(codec, nid, &list);
+	struct snd_array *array = &codec->conn_lists;
+	int len;
+	hda_nid_t *p;
+	bool added = false;
 
-	if (len <= 0)
-		return len;
-	if (len > max_conns) {
+ again:
+	mutex_lock(&codec->hash_mutex);
+	len = -1;
+	/* if the connection-list is already cached, read it */
+	p = lookup_conn_list(array, nid);
+	if (p) {
+		len = p[1];
+		if (conn_list && len > max_conns) {
 			snd_printk(KERN_ERR "hda_codec: "
 				   "Too many connections %d for NID 0x%x\n",
 				   len, nid);
+			mutex_unlock(&codec->hash_mutex);
 			return -EINVAL;
 		}
-	memcpy(conn_list, list, len * sizeof(hda_nid_t));
+		if (conn_list && len)
+			memcpy(conn_list, p + 2, len * sizeof(hda_nid_t));
+	}
+	mutex_unlock(&codec->hash_mutex);
+	if (len >= 0)
+		return len;
+	if (snd_BUG_ON(added))
+		return -EINVAL;
+
+	len = read_and_add_raw_conns(codec, nid);
+	if (len < 0)
 		return len;
+	added = true;
+	goto again;
 }
 EXPORT_SYMBOL_HDA(snd_hda_get_connections);
 
@@ -543,6 +532,7 @@ int snd_hda_override_conn_list(struct hda_codec *codec, hda_nid_t nid, int len,
 	hda_nid_t *p;
 	int i, old_used;
 
+	mutex_lock(&codec->hash_mutex);
 	p = lookup_conn_list(array, nid);
 	if (p)
 		*p = -1; /* invalidate the old entry */
@@ -553,10 +543,12 @@ int snd_hda_override_conn_list(struct hda_codec *codec, hda_nid_t nid, int len,
 	for (i = 0; i < len; i++)
 		if (!add_conn_list(array, list[i]))
 			goto error_add;
+	mutex_unlock(&codec->hash_mutex);
 	return 0;
 
  error_add:
 	array->used = old_used;
+	mutex_unlock(&codec->hash_mutex);
 	return -ENOMEM;
 }
 EXPORT_SYMBOL_HDA(snd_hda_override_conn_list);

sound/pci/hda/hda_codec.h

@@ -911,10 +911,13 @@ int snd_hda_get_sub_nodes(struct hda_codec *codec, hda_nid_t nid,
 			  hda_nid_t *start_id);
 int snd_hda_get_connections(struct hda_codec *codec, hda_nid_t nid,
 			    hda_nid_t *conn_list, int max_conns);
+static inline int
+snd_hda_get_num_conns(struct hda_codec *codec, hda_nid_t nid)
+{
+	return snd_hda_get_connections(codec, nid, NULL, 0);
+}
 int snd_hda_get_raw_connections(struct hda_codec *codec, hda_nid_t nid,
 			    hda_nid_t *conn_list, int max_conns);
-int snd_hda_get_conn_list(struct hda_codec *codec, hda_nid_t nid,
-			  const hda_nid_t **listp);
 int snd_hda_override_conn_list(struct hda_codec *codec, hda_nid_t nid, int nums,
 			  const hda_nid_t *list);
 int snd_hda_get_conn_index(struct hda_codec *codec, hda_nid_t mux,

sound/pci/hda/patch_realtek.c

@@ -349,7 +349,7 @@ static int alc_mux_select(struct hda_codec *codec, unsigned int adc_idx,
 	nid = get_capsrc(spec, adc_idx);
 
 	/* no selection? */
-	num_conns = snd_hda_get_conn_list(codec, nid, NULL);
+	num_conns = snd_hda_get_num_conns(codec, nid);
 	if (num_conns <= 1)
 		return 1;
 
@@ -2543,7 +2543,6 @@ static int alc_auto_fill_adc_caps(struct hda_codec *codec)
 	nid = codec->start_nid;
 	for (i = 0; i < codec->num_nodes; i++, nid++) {
 		hda_nid_t src;
-		const hda_nid_t *list;
 		unsigned int caps = get_wcaps(codec, nid);
 		int type = get_wcaps_type(caps);
 
@@ -2554,6 +2553,7 @@ static int alc_auto_fill_adc_caps(struct hda_codec *codec)
 		src = nid;
 		for (;;) {
 			int n;
+			hda_nid_t conn_nid;
 			type = get_wcaps_type(get_wcaps(codec, src));
 			if (type == AC_WID_PIN)
 				break;
@@ -2561,13 +2561,14 @@ static int alc_auto_fill_adc_caps(struct hda_codec *codec)
 				cap_nids[nums] = src;
 				break;
 			}
-			n = snd_hda_get_conn_list(codec, src, &list);
+			n = snd_hda_get_num_conns(codec, src);
 			if (n > 1) {
 				cap_nids[nums] = src;
 				break;
 			} else if (n != 1)
 				break;
-			src = *list;
+			if (snd_hda_get_connections(codec, src, &src, 1) != 1)
+				break;
 		}
 		if (++nums >= max_nums)
 			break;
@@ -2708,7 +2709,7 @@ static void alc_auto_init_analog_input(struct hda_codec *codec)
 
 	/* mute all loopback inputs */
 	if (spec->mixer_nid) {
-		int nums = snd_hda_get_conn_list(codec, spec->mixer_nid, NULL);
+		int nums = snd_hda_get_num_conns(codec, spec->mixer_nid);
 		for (i = 0; i < nums; i++)
 			snd_hda_codec_write(codec, spec->mixer_nid, 0,
 					    AC_VERB_SET_AMP_GAIN_MUTE,
@@ -3338,7 +3339,7 @@ static int alc_auto_add_sw_ctl(struct hda_codec *codec,
 	if (wid_type == AC_WID_PIN || wid_type == AC_WID_AUD_OUT) {
 		type = ALC_CTL_WIDGET_MUTE;
 		val = HDA_COMPOSE_AMP_VAL(nid, chs, 0, HDA_OUTPUT);
-	} else if (snd_hda_get_conn_list(codec, nid, NULL) == 1) {
+	} else if (snd_hda_get_num_conns(codec, nid) == 1) {
 		type = ALC_CTL_WIDGET_MUTE;
 		val = HDA_COMPOSE_AMP_VAL(nid, chs, 0, HDA_INPUT);
 	} else {
@@ -3898,7 +3899,7 @@ static void alc_remove_invalid_adc_nids(struct hda_codec *codec)
 	nums = 0;
 	for (n = 0; n < spec->num_adc_nids; n++) {
 		hda_nid_t cap = spec->private_capsrc_nids[n];
-		int num_conns = snd_hda_get_conn_list(codec, cap, NULL);
+		int num_conns = snd_hda_get_num_conns(codec, cap);
 		for (i = 0; i < imux->num_items; i++) {
 			hda_nid_t pin = spec->imux_pins[i];
 			if (pin) {
@@ -4027,7 +4028,7 @@ static void select_or_unmute_capsrc(struct hda_codec *codec, hda_nid_t cap,
 	if (get_wcaps_type(get_wcaps(codec, cap)) == AC_WID_AUD_MIX) {
 		snd_hda_codec_amp_stereo(codec, cap, HDA_INPUT, idx,
 					 HDA_AMP_MUTE, 0);
-	} else if (snd_hda_get_conn_list(codec, cap, NULL) > 1) {
+	} else if (snd_hda_get_num_conns(codec, cap) > 1) {
 		snd_hda_codec_write_cache(codec, cap, 0,
 					  AC_VERB_SET_CONNECT_SEL, idx);
 	}

sound/pci/hda/patch_via.c

@@ -485,7 +485,7 @@ static void activate_output_mix(struct hda_codec *codec, struct nid_path *path,
 
 	if (!path)
 		return;
-	num = snd_hda_get_conn_list(codec, mix_nid, NULL);
+	num = snd_hda_get_num_conns(codec, mix_nid);
 	for (i = 0; i < num; i++) {
 		if (i == idx)
 			val = AMP_IN_UNMUTE(i);