Merge changes I1e5a8903,I43c6ad22,If9a102a6,I702e619c into main am: e5b8c171c5 am: 132ab4d211 am: 59703fa923 am: cc558f2f2a am: 5ec1ec09d0

Original change: https://android-review.googlesource.com/c/platform/external/dtc/+/2784253

Change-Id: I7aad50747418f387e4f6e8c01404a2caf6b2316c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

3 files changed, 36 insertions, 27 deletions

diff --git a/libfdt/fdt_ro.c b/libfdt/fdt_ro.c
index 53db8ce..09d92d4 100644
--- a/libfdt/fdt_ro.c
+++ b/libfdt/fdt_ro.c
@@ -10,14 +10,6 @@
 
 #include "libfdt_internal.h"
 
-/* Check if a buffer contains a nul-terminated string.
- * Used for checking property values which should be strings.
- */
-static bool is_nul_string(const char *buf, const size_t buf_len) {
-	return buf_len > 0 && buf[buf_len - 1] == '\0' &&
-		strnlen(buf, buf_len) == buf_len - 1;
-}
-
 static int fdt_nodename_eq_(const void *fdt, int offset,
 			    const char *s, int len)
 {
@@ -533,30 +525,31 @@ uint32_t fdt_get_phandle(const void *fdt, int nodeoffset)
 	return fdt32_ld_(php);
 }
 
+static const void *fdt_path_getprop_namelen(const void *fdt, const char *path,
+					    const char *propname, int propnamelen,
+					    int *lenp)
+{
+	int offset = fdt_path_offset(fdt, path);
+
+	if (offset < 0)
+		return NULL;
+
+	return fdt_getprop_namelen(fdt, offset, propname, propnamelen, lenp);
+}
+
 const char *fdt_get_alias_namelen(const void *fdt,
 				  const char *name, int namelen)
 {
-	const char *prop;
-	int aliasoffset;
-	int prop_len;
+	int len;
+	const char *alias;
 
-	aliasoffset = fdt_path_offset(fdt, "/aliases");
-	if (aliasoffset < 0)
-		return NULL;
+	alias = fdt_path_getprop_namelen(fdt, "/aliases", name, namelen, &len);
 
-	prop = fdt_getprop_namelen(fdt, aliasoffset, name, namelen, &prop_len);
-	if (prop && !can_assume(VALID_INPUT)) {
-		/* Validate the alias value.  From the devicetree spec v0.3:
-		 * "An alias value is a device path and is encoded as a string.
-		 *  The value representes the full path to a node, ..."
-		 * A full path must start at the root to prevent recursion.
-		 */
-		if (prop_len == 0 || *prop != '/' || !is_nul_string(prop, prop_len)) {
-			prop = NULL;
-		}
-	}
+	if (!can_assume(VALID_DTB) &&
+	    !(alias && len > 0 && alias[len - 1] == '\0' && *alias == '/'))
+		return NULL;
 
-	return prop;
+	return alias;
 }
 
 const char *fdt_get_alias(const void *fdt, const char *name)
diff --git a/tests/aliases.dts b/tests/aliases.dts
index 853479a..03ed675 100644
--- a/tests/aliases.dts
+++ b/tests/aliases.dts
@@ -5,6 +5,10 @@
 	#size-cells = <0>;
 
 	aliases {
+		empty = "";
+		loop = "loop";
+		nonull = [626164];
+		relative = "s1/subsubnode";
 		s1 = &sub1;
 		ss1 = &subsub1;
 		sss1 = &subsubsub1;
diff --git a/tests/get_alias.c b/tests/get_alias.c
index fb2c38c..d2888d6 100644
--- a/tests/get_alias.c
+++ b/tests/get_alias.c
@@ -21,9 +21,16 @@ static void check_alias(void *fdt, const char *path, const char *alias)
 
 	aliaspath = fdt_get_alias(fdt, alias);
 
-	if (path && !aliaspath)
+	if (!path && !aliaspath)
+		return;
+
+	if (!aliaspath)
 		FAIL("fdt_get_alias(%s) failed\n", alias);
 
+	if (!path)
+		FAIL("fdt_get_alias(%s) returned %s instead of NULL",
+		     alias, aliaspath);
+
 	if (strcmp(aliaspath, path) != 0)
 		FAIL("fdt_get_alias(%s) returned %s instead of %s\n",
 		     alias, aliaspath, path);
@@ -36,9 +43,14 @@ int main(int argc, char *argv[])
 	test_init(argc, argv);
 	fdt = load_blob_arg(argc, argv);
 
+	check_alias(fdt, NULL, "empty");
+	check_alias(fdt, NULL, "nonull");
+	check_alias(fdt, NULL, "relative");
 	check_alias(fdt, "/subnode@1", "s1");
 	check_alias(fdt, "/subnode@1/subsubnode", "ss1");
 	check_alias(fdt, "/subnode@1/subsubnode/subsubsubnode", "sss1");
 
+	check_alias(fdt, NULL, "loop"); // Might trigger a stack overflow
+
 	PASS();
 }