ASoC: core: check of_property_count_strings failure

Signed-off-by: Richard Zhao <richard.zhao@freescale.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: stable@vger.kernel.org
diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index 3a4e93e..b390f00 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -3631,10 +3631,10 @@
 	int i, ret;
 
 	num_routes = of_property_count_strings(np, propname);
-	if (num_routes & 1) {
+	if (num_routes < 0 || num_routes & 1) {
 		dev_err(card->dev,
-			"Property '%s's length is not even\n",
-			propname);
+		     "Property '%s' does not exist or its length is not even\n",
+		     propname);
 		return -EINVAL;
 	}
 	num_routes /= 2;