[PATCH v3] fdt_region: Check return value of fdt_get_property_by_offset() calls

[Anton Ivanov]

fdt_get_property_by_offset() returns NULL for FDT with version
less than 0x10. Callers in fdt_find_regions(),
fdt_add_alias_regions(), and fdt_next_region() dereference the
result without checking, leading to a NULL pointer dereference.

Add NULL checks before accessing the returned property pointer.
Also add a missing NULL check for fdt_string() in
fdt_add_alias_regions() and fdt_next_region().

Signed-off-by: Anton Ivanov <anton at binarly.io>
---
Changes in v3:
- Update From and Signed-off-by to personal email

Changes in v2:
- Rewrite commit message to be concise per maintainer feedback

 boot/fdt_region.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/boot/fdt_region.c b/boot/fdt_region.c
index 295ea08ac91..0a9d47bb2bd 100644
--- a/boot/fdt_region.c
+++ b/boot/fdt_region.c
@@ -69,6 +69,8 @@ int fdt_find_regions(const void *fdt, char * const inc[], int inc_count,
 			include = want >= 2;
 			stop_at = offset;
 			prop = fdt_get_property_by_offset(fdt, offset, NULL);
+			if (!prop)
+				return -FDT_ERR_BADSTRUCTURE;
 			str = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
 			if (!str)
 				return -FDT_ERR_BADSTRUCTURE;
@@ -271,7 +273,11 @@ int fdt_add_alias_regions(const void *fdt, struct fdt_region *region, int count,
 		int target, next;
 
 		prop = fdt_get_property_by_offset(fdt, offset, NULL);
+		if (!prop)
+			return -FDT_ERR_BADSTRUCTURE;
 		name = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
+		if (!name)
+			return -FDT_ERR_BADSTRUCTURE;
 		target = fdt_path_offset(fdt, name);
 		if (!region_list_contains_offset(info, fdt, target))
 			continue;
@@ -520,7 +526,11 @@ int fdt_next_region(const void *fdt,
 		case FDT_PROP:
 			stop_at = offset;
 			prop = fdt_get_property_by_offset(fdt, offset, NULL);
+			if (!prop)
+				return -FDT_ERR_BADSTRUCTURE;
 			str = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
+			if (!str)
+				return -FDT_ERR_BADSTRUCTURE;
 			val = h_include(priv, fdt, last_node, FDT_IS_PROP, str,
 					    strlen(str) + 1);
 			if (val == -1) {
-- 
2.53.0