[PATCH v2] interconnect: imx: fix use-after-free in imx_icc_node_init_qos()

[Wentao Liang]

The function imx_icc_node_init_qos() manually manages the reference count
of struct device_node *dn using of_node_put(). However, some error paths
use dn after the put, leading to use-after-free. Convert to automatic
cleanup using __free(device_node) to ensure the reference is always
released when dn goes out of scope.

Fixes: f0d8048525d7 ("interconnect: Add imx core driver")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Wentao Liang <vulab@xxxxxxxxxxx>
---
Changes in v2:
- Use auto cheanup to fix the problem.
---
 drivers/interconnect/imx/imx.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/interconnect/imx/imx.c b/drivers/interconnect/imx/imx.c
index 9511f80cf041..e5fcdcb88cfb 100644
--- a/drivers/interconnect/imx/imx.c
+++ b/drivers/interconnect/imx/imx.c
@@ -120,7 +120,8 @@ static int imx_icc_node_init_qos(struct icc_provider *provider,
 	struct imx_icc_node *node_data = node->data;
 	const struct imx_icc_node_adj_desc *adj = node_data->desc->adj;
 	struct device *dev = provider->dev;
-	struct device_node *dn = NULL;
+	struct device_node *__free(device_nod) dn = of_parse_phandle(dev->of_node,
+			adj->phandle_name, 0);
 	struct platform_device *pdev;
 
 	if (adj->main_noc) {
@@ -128,7 +129,6 @@ static int imx_icc_node_init_qos(struct icc_provider *provider,
 		dev_dbg(dev, "icc node %s[%d] is main noc itself\n",
 			node->name, node->id);
 	} else {
-		dn = of_parse_phandle(dev->of_node, adj->phandle_name, 0);
 		if (!dn) {
 			dev_warn(dev, "Failed to parse %s\n",
 				 adj->phandle_name);
@@ -138,12 +138,10 @@ static int imx_icc_node_init_qos(struct icc_provider *provider,
 		if (!of_device_is_available(dn)) {
 			dev_warn(dev, "Missing property %s, skip scaling %s\n",
 				 adj->phandle_name, node->name);
-			of_node_put(dn);
 			return 0;
 		}
 
 		pdev = of_find_device_by_node(dn);
-		of_node_put(dn);
 		if (!pdev) {
 			dev_warn(dev, "node %s[%d] missing device for %pOF\n",
 				 node->name, node->id, dn);
-- 
2.34.1