[PATCH] ASoC: audio-graph-card: fix an use-after-free in graph_get_dai_id()

[Wen Yang]

After calling of_node_put() on the node variable, it is still being
used, which may result in use-after-free.
Fix this issue by calling of_node_put() after the last usage.

Fixes: a0c426fe1433 ("ASoC: simple-card-utils: check "reg" property on asoc_simple_card_get_dai_id()")
Link: https://lore.kernel.org/r/1562743509-30496-5-git-send-email-wen.yang99@xxxxxxxxxx
Signed-off-by: Wen Yang <wen.yang99@xxxxxxxxxx>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
---
 sound/soc/generic/audio-graph-card.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sound/soc/generic/audio-graph-card.c b/sound/soc/generic/audio-graph-card.c
index bddfcfd7bedf..343ede8042c3 100644
--- a/sound/soc/generic/audio-graph-card.c
+++ b/sound/soc/generic/audio-graph-card.c
@@ -63,6 +63,7 @@ static int graph_get_dai_id(struct device_node *ep)
 	struct device_node *endpoint;
 	struct of_endpoint info;
 	int i, id;
+	u32 *reg;
 	int ret;
 
 	/* use driver specified DAI ID if exist */
@@ -83,8 +84,9 @@ static int graph_get_dai_id(struct device_node *ep)
 			return info.id;
 
 		node = of_get_parent(ep);
+		reg = of_get_property(node, "reg", NULL);
 		of_node_put(node);
-		if (of_get_property(node, "reg", NULL))
+		if (reg)
 			return info.port;
 	}
 	node = of_graph_get_port_parent(ep);
-- 
2.20.1