[PATCH 3/4] tools: kwbimage: Verify size of image data

[Pali Rohár]

Part of image data is 4 byte checksum, so every image must contain at least
4 bytes. Verify it to prevent memory corruptions.

Signed-off-by: Pali Rohár <pali at kernel.org>
---
 tools/kwbimage.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/kwbimage.c b/tools/kwbimage.c
index 84c41210e39e..5ac34ac5e9c8 100644
--- a/tools/kwbimage.c
+++ b/tools/kwbimage.c
@@ -1757,7 +1757,7 @@ static int kwbimage_verify_header(unsigned char *ptr, int image_size,
 			return -FDT_ERR_BADSTRUCTURE;
 
 		size = le32_to_cpu(mhdr->blocksize);
-		if (offset + size > image_size || size % 4 != 0)
+		if (size < 4 || offset + size > image_size || size % 4 != 0)
 			return -FDT_ERR_BADSTRUCTURE;
 
 		if (image_checksum32(ptr + offset, size - 4) !=
-- 
2.20.1