[PATCH] bus: vexpress-config: fix device_node refcount leak in vexpress_syscfg_probe()

[Weigang He <geoffreyhe2@gmail.com>]

vexpress_syscfg_probe() iterates the "arm,vexpress,config-bus"
compatible nodes and, for each one, takes a reference to the bridge
phandle via of_parse_phandle():

	bridge_np = of_parse_phandle(node, "arm,vexpress,config-bridge", 0);

bridge_np is only compared against pdev->dev.parent->of_node and is
never released - neither on the "continue" path when it does not match,
nor on the path that calls of_platform_populate() and falls through to
the next loop iteration. Each matching iteration leaks one device_node
reference; the leak repeats on every probe (driver bind/unbind, module
reload, or EPROBE_DEFER retry).

This is a regression of commit 557e37c05f28 ("bus: vexpress-config: add
missing of_node_put after calling of_parse_phandle"), which fixed the
equivalent leak in the predecessor function vexpress_config_populate().
Commit a5a38765ac79 ("bus: vexpress-config: simplify config bus
probing") removed that function and inlined the loop into the probe
routine, but did not carry over the of_node_put().

Use the __free(device_node) cleanup attribute on bridge_np so the
reference is released automatically at the end of each loop iteration.

Found by static analysis tool CodeQL.

Fixes: a5a38765ac79 ("bus: vexpress-config: simplify config bus probing")
Signed-off-by: Weigang He <geoffreyhe2@gmail.com>
---
 drivers/bus/vexpress-config.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/bus/vexpress-config.c b/drivers/bus/vexpress-config.c
index 64ee920721ee7..cc247483d3823 100644
--- a/drivers/bus/vexpress-config.c
+++ b/drivers/bus/vexpress-config.c
@@ -390,9 +390,9 @@ static int vexpress_syscfg_probe(struct platform_device *pdev)
 	}
 
 	for_each_compatible_node(node, NULL, "arm,vexpress,config-bus") {
-		struct device_node *bridge_np;
+		struct device_node *bridge_np __free(device_node) =
+			of_parse_phandle(node, "arm,vexpress,config-bridge", 0);
 
-		bridge_np = of_parse_phandle(node, "arm,vexpress,config-bridge", 0);
 		if (bridge_np != pdev->dev.parent->of_node)
 			continue;
 

base-commit: 0f61b1860cc3f52aef9036d7235ed1f017632193
-- 
2.43.0