diff --git a/lib/libfdt/fdt.c b/lib/libfdt/fdt.c
index 9fe7cf4..20c6415 100644
--- a/lib/libfdt/fdt.c
+++ b/lib/libfdt/fdt.c
@@ -106,7 +106,6 @@
 	}
 	hdrsize = fdt_header_size(fdt);
 	if (!can_assume(VALID_DTB)) {
-
 		if ((fdt_totalsize(fdt) < hdrsize)
 		    || (fdt_totalsize(fdt) > INT_MAX))
 			return -FDT_ERR_TRUNCATED;
@@ -115,9 +114,7 @@
 		if (!check_off_(hdrsize, fdt_totalsize(fdt),
 				fdt_off_mem_rsvmap(fdt)))
 			return -FDT_ERR_TRUNCATED;
-	}
 
-	if (!can_assume(VALID_DTB)) {
 		/* Bounds check structure block */
 		if (!can_assume(LATEST) && fdt_version(fdt) < 17) {
 			if (!check_off_(hdrsize, fdt_totalsize(fdt),
@@ -165,7 +162,7 @@
 uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
 {
 	const fdt32_t *tagp, *lenp;
-	uint32_t tag;
+	uint32_t tag, len, sum;
 	int offset = startoffset;
 	const char *p;
 
@@ -191,12 +188,19 @@
 		lenp = fdt_offset_ptr(fdt, offset, sizeof(*lenp));
 		if (!can_assume(VALID_DTB) && !lenp)
 			return FDT_END; /* premature end */
+
+		len = fdt32_to_cpu(*lenp);
+		sum = len + offset;
+		if (!can_assume(VALID_DTB) &&
+		    (INT_MAX <= sum || sum < (uint32_t) offset))
+			return FDT_END; /* premature end */
+
 		/* skip-name offset, length and value */
-		offset += sizeof(struct fdt_property) - FDT_TAGSIZE
-			+ fdt32_to_cpu(*lenp);
+		offset += sizeof(struct fdt_property) - FDT_TAGSIZE + len;
+
 		if (!can_assume(LATEST) &&
-		    fdt_version(fdt) < 0x10 && fdt32_to_cpu(*lenp) >= 8 &&
-		    ((offset - fdt32_to_cpu(*lenp)) % 8) != 0)
+		    fdt_version(fdt) < 0x10 && len >= 8 &&
+		    ((offset - len) % 8) != 0)
 			offset += 4;
 		break;