vboot: Do not use hashed-strings offset

The hashed-strings signature property includes two uint32_t values.
The first is unneeded as there should never be a start offset into the
strings region. The second, the size, is needed because the added
signature node appends to this region.

See tools/image-host.c, where a static 0 value is used for the offset.

Signed-off-by: Teddy Reed <teddy.reed@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

common/image-sig.c

@@ -377,8 +377,11 @@ int fit_config_check_sig(const void *fit, int noffset, int required_keynode,
 	/* Add the strings */
 	strings = fdt_getprop(fit, noffset, "hashed-strings", NULL);
 	if (strings) {
-		fdt_regions[count].offset = fdt_off_dt_strings(fit) +
-				fdt32_to_cpu(strings[0]);
+		/*
+		 * The strings region offset must be a static 0x0.
+		 * This is set in tool/image-host.c
+		 */
+		fdt_regions[count].offset = fdt_off_dt_strings(fit);
 		fdt_regions[count].size = fdt32_to_cpu(strings[1]);
 		count++;
 	}

tools/image-host.c

@@ -135,6 +135,7 @@ static int fit_image_write_sig(void *fit, int noffset, uint8_t *value,
 
 		ret = fdt_setprop(fit, noffset, "hashed-nodes",
 				   region_prop, region_proplen);
+		/* This is a legacy offset, it is unused, and must remain 0. */
 		strdata[0] = 0;
 		strdata[1] = cpu_to_fdt32(string_size);
 		if (!ret) {