[PATCH 6.12 049/117] bus: fsl-mc: Fix potential double device reference in fsl_mc_get_endpoint()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ma Ke <make24@iscas.ac.cn>

commit bddbe13d36a02d5097b99cf02354d5752ad1ac60 upstream.

The fsl_mc_get_endpoint() function may call fsl_mc_device_lookup()
twice, which would increment the device's reference count twice if
both lookups find a device. This could lead to a reference count leak.

Found by code review.

Cc: stable@vger.kernel.org
Fixes: 1ac210d128ef ("bus: fsl-mc: add the fsl_mc_get_endpoint function")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
Tested-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Fixes: 8567494cebe5 ("bus: fsl-mc: rescan devices if endpoint not found")
Link: https://patch.msgid.link/20250717022309.3339976-1-make24@iscas.ac.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/bus/fsl-mc/fsl-mc-bus.c |   19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

--- a/drivers/bus/fsl-mc/fsl-mc-bus.c
+++ b/drivers/bus/fsl-mc/fsl-mc-bus.c
@@ -942,6 +942,7 @@ struct fsl_mc_device *fsl_mc_get_endpoin
 	struct fsl_mc_obj_desc endpoint_desc = {{ 0 }};
 	struct dprc_endpoint endpoint1 = {{ 0 }};
 	struct dprc_endpoint endpoint2 = {{ 0 }};
+	struct fsl_mc_bus *mc_bus;
 	int state, err;
 
 	mc_bus_dev = to_fsl_mc_device(mc_dev->dev.parent);
@@ -965,6 +966,8 @@ struct fsl_mc_device *fsl_mc_get_endpoin
 	strcpy(endpoint_desc.type, endpoint2.type);
 	endpoint_desc.id = endpoint2.id;
 	endpoint = fsl_mc_device_lookup(&endpoint_desc, mc_bus_dev);
+	if (endpoint)
+		return endpoint;
 
 	/*
 	 * We know that the device has an endpoint because we verified by
@@ -972,17 +975,13 @@ struct fsl_mc_device *fsl_mc_get_endpoin
 	 * yet discovered by the fsl-mc bus, thus the lookup returned NULL.
 	 * Force a rescan of the devices in this container and retry the lookup.
 	 */
-	if (!endpoint) {
-		struct fsl_mc_bus *mc_bus = to_fsl_mc_bus(mc_bus_dev);
-
-		if (mutex_trylock(&mc_bus->scan_mutex)) {
-			err = dprc_scan_objects(mc_bus_dev, true);
-			mutex_unlock(&mc_bus->scan_mutex);
-		}
-
-		if (err < 0)
-			return ERR_PTR(err);
+	mc_bus = to_fsl_mc_bus(mc_bus_dev);
+	if (mutex_trylock(&mc_bus->scan_mutex)) {
+		err = dprc_scan_objects(mc_bus_dev, true);
+		mutex_unlock(&mc_bus->scan_mutex);
 	}
+	if (err < 0)
+		return ERR_PTR(err);
 
 	endpoint = fsl_mc_device_lookup(&endpoint_desc, mc_bus_dev);
 	/*