[PATCH] device property: fix fwnode reference leak in fwnode_graph_get_endpoint_by_id()

[Stepan Ionichev]

When called with FWNODE_GRAPH_ENDPOINT_NEXT, the function walks every
endpoint under the requested port and, for any endpoint whose ID is
greater than or equal to the requested one, may store a fwnode
reference in best_ep via fwnode_handle_get(). If a later iteration
finds an exact-ID match, the function returns that endpoint directly
without dropping the reference held by best_ep, leaking it.

Drop the saved candidate before returning the exact-match endpoint.

This affects callers that use FWNODE_GRAPH_ENDPOINT_NEXT to ask for
the next endpoint with ID >= the requested one (used by a number of
media drivers, e.g. imx7/8, sun6i CSI, omap3isp, xilinx-csi2,
stm32-csi). Each leak retains a fwnode reference until reboot/unbind.

Fixes: 0fcc2bdc8aff ("device property: Add fwnode_graph_get_endpoint_by_id()")
Signed-off-by: Stepan Ionichev <sozdayvek@xxxxxxxxx>
---
 drivers/base/property.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index 8e0148a37..e08eadd66 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -1277,8 +1277,10 @@ fwnode_graph_get_endpoint_by_id(const struct fwnode_handle *fwnode,
 		if (fwnode_ep.port != port)
 			continue;
 
-		if (fwnode_ep.id == endpoint)
+		if (fwnode_ep.id == endpoint) {
+			fwnode_handle_put(best_ep);
 			return ep;
+		}
 
 		if (!endpoint_next)
 			continue;
-- 
2.43.0