[PATCH 1/2] of: overlay: of_overlay_fix_path: allow symbols without __overlay__

[Stefan Kerkmann <s.kerkmann@pengutronix.de>]

An overlay with a label entry in the `__symbols__` table without a
matching fragment that contains an `__overlay__` is not an error. This
matches the behavior of the dtc libfdt implementation[1].

This edge case was triggered by:

1. Enabling CONFIG_OF_OVERLAY_LIVE this adds a `__symbols__` table to
   device trees compiled by barebox.

2. Passing the barebox devicetree via TF-A to OP-TEE that adds overlay
   fragments to the barebox device tree.

3. Enabling CONFIG_OPTEE_APPLY_OVERLAY and applying the same DT again as
   a DT overlay. The DT in this case was expanded by OP-TEE with overlay
   fragments (and still contains the __symbol__ table with entries that
   do not reference the OP-TEE fragments).

[1]: 5c715a4 ("fdtoverlay: Ignore symbols in overlays which don't apply to the target tree")

Fixes: 6553d2c2a5e3 ("of: overlay: avoid potential null pointer exception")
Signed-off-by: Stefan Kerkmann <s.kerkmann@pengutronix.de>
---
 drivers/of/overlay.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index 4ce45513ea..410c6d3565 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -110,13 +110,13 @@ static char *of_overlay_fix_path(struct device_node *root,
 			break;
 	}
 	if (!fragment) {
-		pr_info("could not find __overlay__ node\n");
+		pr_debug("could not find __overlay__ node for %s\n", path);
 		return NULL;
 	}
 
 	target = find_target(root, fragment, false);
 	if (!target)
-		return NULL;
+		return ERR_PTR(-EINVAL);
 
 	prefix = of_get_child_by_name(fragment, "__overlay__")->full_name;
 	path_tail = path + strlen(prefix);
@@ -152,8 +152,10 @@ static int of_overlay_apply_symbols(struct device_node *root,
 
 		old_path = of_property_get_value(prop);
 		new_path = of_overlay_fix_path(root, overlay, old_path);
+		if (IS_ERR(new_path))
+			return PTR_ERR(new_path);
 		if (!new_path)
-			return -EINVAL;
+			continue;
 
 		pr_debug("add symbol %s with new path %s\n",
 			 prop->name, new_path);

-- 
2.47.3