[PATCH] image: Fix potentially uninitialized data variable

[Marek Vasut]

In case fitImage support is disabled, and image_locate_script() is
passed a fitImage, then the 'data' variable is used uninitialized.
Drop into the default: branch of the switch-case statement and do
not return the uninitialized data, and do not modify the return
pointer either, just print an error message.

Reported by clang build:
"
$ make HOSTCC=clang CC=clang KCFLAGS=-Werror sandbox64_defconfig && make HOSTCC=clang CC=clang KCFLAGS=-Werror
...
boot/image-board.c:1006:7: error: variable 'data' is used uninitialized whenever switch case is taken [-Werror,-Wsometimes-uninitialized]
        case IMAGE_FORMAT_LEGACY:
             ^~~~~~~~~~~~~~~~~~~
include/image.h:608:29: note: expanded from macro 'IMAGE_FORMAT_LEGACY'
                                ^~~~
boot/image-board.c:1128:19: note: uninitialized use occurs here
        *datap = (char *)data;
                         ^~~~
boot/image-board.c:1001:11: note: initialize the variable 'data' to silence this warning
        u32 *data;
                 ^
                  = NULL
"

Signed-off-by: Marek Vasut <marek.vasut+renesas at mailbox.org>
---
Cc: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
Cc: Michal Simek <michal.simek at amd.com>
Cc: Oleksandr Suvorov <oleksandr.suvorov at foundries.io>
Cc: Simon Glass <sjg at chromium.org>
Cc: Stefan Roese <sr at denx.de>
Cc: Tom Rini <trini at konsulko.com>
---
 boot/image-board.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/boot/image-board.c b/boot/image-board.c
index 25b60ec30b3..9bf70824cb7 100644
--- a/boot/image-board.c
+++ b/boot/image-board.c
@@ -1004,7 +1004,9 @@ int image_locate_script(void *buf, int size, const char *fit_uname,
 
 	switch (genimg_get_format(buf)) {
 	case IMAGE_FORMAT_LEGACY:
-		if (IS_ENABLED(CONFIG_LEGACY_IMAGE_FORMAT)) {
+		if (!IS_ENABLED(CONFIG_LEGACY_IMAGE_FORMAT)) {
+			goto exit_image_format;
+		} else {
 			hdr = buf;
 
 			if (!image_check_magic(hdr)) {
@@ -1047,7 +1049,9 @@ int image_locate_script(void *buf, int size, const char *fit_uname,
 		}
 		break;
 	case IMAGE_FORMAT_FIT:
-		if (IS_ENABLED(CONFIG_FIT)) {
+		if (!IS_ENABLED(CONFIG_FIT)) {
+			goto exit_image_format;
+		} else {
 			fit_hdr = buf;
 			if (fit_check_format(fit_hdr, IMAGE_SIZE_INVAL)) {
 				puts("Bad FIT image format\n");
@@ -1121,12 +1125,15 @@ fallback:
 		}
 		break;
 	default:
-		puts("Wrong image format for \"source\" command\n");
-		return -EPERM;
+		goto exit_image_format;
 	}
 
 	*datap = (char *)data;
 	*lenp = len;
 
 	return 0;
+
+exit_image_format:
+	puts("Wrong image format for \"source\" command\n");
+	return -EPERM;
 }
-- 
2.39.2