platform/x86/intel/ifs: Validate image size

Perform additional validation prior to loading IFS image.

Error out if the size of the file being loaded doesn't match the size
specified in the header.
Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Tested-by: Pengfei Xu <pengfei.xu@intel.com>
Link: https://lore.kernel.org/r/20231005195137.3117166-6-jithu.joseph@intel.comSigned-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

drivers/platform/x86/intel/ifs/load.c

@@ -375,6 +375,7 @@ int ifs_load_firmware(struct device *dev)
 {
 	const struct ifs_test_caps *test = ifs_get_test_caps(dev);
 	struct ifs_data *ifsd = ifs_get_data(dev);
+	unsigned int expected_size;
 	const struct firmware *fw;
 	char scan_path[64];
 	int ret = -EINVAL;
@@ -389,6 +390,13 @@ int ifs_load_firmware(struct device *dev)
 		goto done;
 	}
 
+	expected_size = ((struct microcode_header_intel *)fw->data)->totalsize;
+	if (fw->size != expected_size) {
+		dev_err(dev, "File size mismatch (expected %u, actual %zu). Corrupted IFS image.\n",
+			expected_size, fw->size);
+		return -EINVAL;
+	}
+
 	ret = image_sanity_check(dev, (struct microcode_header_intel *)fw->data);
 	if (ret)
 		goto release;