serial/sunsu: fix refcount leak

[ Upstream commit d430aff8cd0c57502d873909c184e3b5753f8b88 ]

The function of_find_node_by_path() acquires a reference to the node
returned by it and that reference needs to be dropped by its caller.

su_get_type() doesn't do that. The match node are used as an identifier
to compare against the current node, so we can directly drop the refcount
after getting the node from the path as it is not used as pointer.

Fix this by use a single variable and drop the refcount right after
of_find_node_by_path().

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/tty/serial/sunsu.c b/drivers/tty/serial/sunsu.c
index 95d34d7565c9aabe5f734c21070a505d77f10043..1cf78cec746164f68b4d2f958bbf8880cb9f2485 100644 (file)
--- a/drivers/tty/serial/sunsu.c
+++ b/drivers/tty/serial/sunsu.c
@@ -1393,22 +1393,43 @@ static inline struct console *SUNSU_CONSOLE(void)
 static enum su_type su_get_type(struct device_node *dp)
 {
        struct device_node *ap = of_find_node_by_path("/aliases");
+       enum su_type rc = SU_PORT_PORT;
 
        if (ap) {
                const char *keyb = of_get_property(ap, "keyboard", NULL);
                const char *ms = of_get_property(ap, "mouse", NULL);
+               struct device_node *match;
 
                if (keyb) {
-                       if (dp == of_find_node_by_path(keyb))
-                               return SU_PORT_KBD;
+                       match = of_find_node_by_path(keyb);
+
+                       /*
+                        * The pointer is used as an identifier not
+                        * as a pointer, we can drop the refcount on
+                        * the of__node immediately after getting it.
+                        */
+                       of_node_put(match);
+
+                       if (dp == match) {
+                               rc = SU_PORT_KBD;
+                               goto out;
+                       }
                }
                if (ms) {
-                       if (dp == of_find_node_by_path(ms))
-                               return SU_PORT_MS;
+                       match = of_find_node_by_path(ms);
+
+                       of_node_put(match);
+
+                       if (dp == match) {
+                               rc = SU_PORT_MS;
+                               goto out;
+                       }
                }
        }
 
-       return SU_PORT_PORT;
+out:
+       of_node_put(ap);
+       return rc;
 }
 
 static int su_probe(struct platform_device *op)