[PATCH] pmdomain: mediatek: fix remaining %pOF after of_node_put()

[Guangshuo Li]

scpsys_get_bus_protection_legacy() looks up several legacy bus
protection regmaps from device-tree nodes.

Two error paths put the device node before checking whether the regmap
lookup failed, but still pass that node to dev_err_probe() with %pOF on
failure. If of_node_put() drops the last reference, the later %pOF
formatting can dereference a freed device node.

Keep the node reference until after the error message has been emitted in
the infracfg and SMI lookup paths. Also drop the SMI node before
returning when the SMI phandle is missing.

Fixes: c29345fa5f66 ("pmdomain: mediatek: Refactor bus protection regmaps retrieval")
Signed-off-by: Guangshuo Li <lgs201920130244 at gmail.com>
---
 drivers/pmdomain/mediatek/mtk-pm-domains.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/drivers/pmdomain/mediatek/mtk-pm-domains.c b/drivers/pmdomain/mediatek/mtk-pm-domains.c
index e1cfd4223473..f877d6694dd5 100644
--- a/drivers/pmdomain/mediatek/mtk-pm-domains.c
+++ b/drivers/pmdomain/mediatek/mtk-pm-domains.c
@@ -1032,12 +1032,15 @@ static int scpsys_get_bus_protection_legacy(struct device *dev, struct scpsys *s
 	node = of_find_node_with_property(np, "mediatek,infracfg");
 	if (node) {
 		regmap[0] = syscon_regmap_lookup_by_phandle(node, "mediatek,infracfg");
-		of_node_put(node);
 		num_regmaps++;
-		if (IS_ERR(regmap[0]))
-			return dev_err_probe(dev, PTR_ERR(regmap[0]),
+		if (IS_ERR(regmap[0])) {
+			ret = dev_err_probe(dev, PTR_ERR(regmap[0]),
 					     "%pOF: failed to get infracfg regmap\n",
 					     node);
+			of_node_put(node);
+			return ret;
+		}
+		of_node_put(node);
 	} else {
 		regmap[0] = NULL;
 	}
@@ -1046,17 +1049,22 @@ static int scpsys_get_bus_protection_legacy(struct device *dev, struct scpsys *s
 	node = of_find_node_with_property(np, "mediatek,smi");
 	if (node) {
 		smi_np = of_parse_phandle(node, "mediatek,smi", 0);
-		of_node_put(node);
-		if (!smi_np)
+		if (!smi_np) {
+			of_node_put(node);
 			return -ENODEV;
+		}
 
 		regmap[1] = device_node_to_regmap(smi_np);
 		num_regmaps++;
 		of_node_put(smi_np);
-		if (IS_ERR(regmap[1]))
-			return dev_err_probe(dev, PTR_ERR(regmap[1]),
+		if (IS_ERR(regmap[1])) {
+			ret = dev_err_probe(dev, PTR_ERR(regmap[1]),
 					     "%pOF: failed to get SMI regmap\n",
 					     node);
+			of_node_put(node);
+			return ret;
+		}
+		of_node_put(node);
 	} else {
 		regmap[1] = NULL;
 	}
-- 
2.43.0