reset: Fix potential use-after-free in __of_reset_control_get()

[ Upstream commit b790c8ea ]

Calling of_node_put() decreases the reference count of a device tree
object, and may free some data.

However, the of_phandle_args structure embedding it is passed to
reset_controller_dev.of_xlate() after that, so it may still be accessed.

Move the call to of_node_put() down to fix this.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
[p.zabel@pengutronix.de: moved of_node_put after mutex_unlock]
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/reset/core.c

@@ -496,28 +496,29 @@ struct reset_control *__of_reset_control_get(struct device_node *node,
 			break;
 		}
 	}
-	of_node_put(args.np);
 
 	if (!rcdev) {
-		mutex_unlock(&reset_list_mutex);
-		return ERR_PTR(-EPROBE_DEFER);
+		rstc = ERR_PTR(-EPROBE_DEFER);
+		goto out;
 	}
 
 	if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
-		mutex_unlock(&reset_list_mutex);
-		return ERR_PTR(-EINVAL);
+		rstc = ERR_PTR(-EINVAL);
+		goto out;
 	}
 
 	rstc_id = rcdev->of_xlate(rcdev, &args);
 	if (rstc_id < 0) {
-		mutex_unlock(&reset_list_mutex);
-		return ERR_PTR(rstc_id);
+		rstc = ERR_PTR(rstc_id);
+		goto out;
 	}
 
 	/* reset_list_mutex also protects the rcdev's reset_control list */
 	rstc = __reset_control_get_internal(rcdev, rstc_id, shared);
 
+out:
 	mutex_unlock(&reset_list_mutex);
+	of_node_put(args.np);
 
 	return rstc;
 }