linux-kernel - [PATCH v4] of: dynamic: fix memory leak related to properties of __of_node

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Message-ID: <1508464749-54218-1-git-send-email-alan.1.wang@nokia-sbell.com>
Date:   Fri, 20 Oct 2017 09:59:09 +0800
From:   Lixin Wang <alan.1.wang@...ia-sbell.com>
To:     Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>
CC:     <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        Lixin Wang <alan.1.wang@...ia-sbell.com>
Subject: [PATCH v4] of: dynamic: fix memory leak related to properties of __of_node_dup

If a node with no properties is dynamically added, then a property is
dynamically added to the node, then the property is dynamically removed,
the result will be node->properties == NULL and node->deadprops != NULL.

Add a separate function to release the properties in both lists.

Signed-off-by: Lixin Wang <alan.1.wang@...ia-sbell.com>
Reviewed-by: Frank Rowand <frank.rowand@...y.com>
---
Thanks the idea from Rob Herring, that I forgot to mention at patch v3.
Thanks Frank Rowand for writing to me the example.

v3 -> v4:
 * Using the style that is more consistent with device tree 
   code, as suggested by Frank Rowand

 drivers/of/dynamic.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
index 301b6db..f33b7c2 100644
--- a/drivers/of/dynamic.c
+++ b/drivers/of/dynamic.c
@@ -315,6 +315,17 @@ int of_detach_node(struct device_node *np)
 }
 EXPORT_SYMBOL_GPL(of_detach_node);
 
+static void property_list_free(struct property *prop_list)
+{
+	struct property *prop;
+
+	for (prop = prop_list; prop != NULL; prop = prop->next) {
+		kfree(prop->name);
+		kfree(prop->value);
+		kfree(prop);
+	}
+}
+
 /**
  * of_node_release() - release a dynamically allocated node
  * @kref: kref element of the node to be released
@@ -324,7 +335,6 @@ EXPORT_SYMBOL_GPL(of_detach_node);
 void of_node_release(struct kobject *kobj)
 {
 	struct device_node *node = kobj_to_device_node(kobj);
-	struct property *prop = node->properties;
 
 	/* We should never be releasing nodes that haven't been detached. */
 	if (!of_node_check_flag(node, OF_DETACHED)) {
@@ -335,18 +345,9 @@ void of_node_release(struct kobject *kobj)
 	if (!of_node_check_flag(node, OF_DYNAMIC))
 		return;
 
-	while (prop) {
-		struct property *next = prop->next;
-		kfree(prop->name);
-		kfree(prop->value);
-		kfree(prop);
-		prop = next;
+	property_list_free(node->properties);
+	property_list_free(node->deadprops);
 
-		if (!prop) {
-			prop = node->deadprops;
-			node->deadprops = NULL;
-		}
-	}
 	kfree(node->full_name);
 	kfree(node->data);
 	kfree(node);
-- 
2.6.2