linux-kernel - [PATCH 1/2] device property: do not leak child nodes when using NULL/error pointers

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Message-ID: <20241128053937.4076797-1-dmitry.torokhov@gmail.com>
Date: Wed, 27 Nov 2024 21:39:34 -0800
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Daniel Scally <djrscally@...il.com>
Cc: linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] device property: do not leak child nodes when using NULL/error pointers

The documentation to various API calls that locate children for a given
fwnode (such as fwnode_get_next_available_child_node() or
device_get_next_child_node()) states that the reference to the node
passed in "child" argument is dropped unconditionally, however the
change that added checks for the main node to be NULL or error pointer
broke this promise.

Add missing fwnode_handle_put() calls to restore the documented
behavior.

Fixes: 002752af7b89 ("device property: Allow error pointer to be passed to fwnode APIs")
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
---
 drivers/base/property.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index 837d77e3af2b..696ba43b8e8a 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -759,6 +759,12 @@ struct fwnode_handle *
 fwnode_get_next_child_node(const struct fwnode_handle *fwnode,
 			   struct fwnode_handle *child)
 {
+	if (IS_ERR_OR_NULL(fwnode) ||
+	    !fwnode_has_op(fwnode, get_next_child_node)) {
+		fwnode_handle_put(child);
+		return NULL;
+	}
+
 	return fwnode_call_ptr_op(fwnode, get_next_child_node, child);
 }
 EXPORT_SYMBOL_GPL(fwnode_get_next_child_node);
@@ -778,9 +784,6 @@ fwnode_get_next_available_child_node(const struct fwnode_handle *fwnode,
 {
 	struct fwnode_handle *next_child = child;
 
-	if (IS_ERR_OR_NULL(fwnode))
-		return NULL;
-
 	do {
 		next_child = fwnode_get_next_child_node(fwnode, next_child);
 		if (!next_child)
@@ -806,8 +809,10 @@ struct fwnode_handle *device_get_next_child_node(const struct device *dev,
 	const struct fwnode_handle *fwnode = dev_fwnode(dev);
 	struct fwnode_handle *next;
 
-	if (IS_ERR_OR_NULL(fwnode))
+	if (IS_ERR_OR_NULL(fwnode)) {
+		fwnode_handle_put(child);
 		return NULL;
+	}
 
 	/* Try to find a child in primary fwnode */
 	next = fwnode_get_next_child_node(fwnode, child);
-- 
2.47.0.338.g60cca15819-goog