[PATCH] image: Ensure image header name is null terminated

[Joel Stanley]

When building with GCC 12:

../include/image.h:779:9: warning: ‘strncpy’ specified bound 32 equals destination size [-Wstringop-truncation]
  779 |         strncpy(image_get_name(hdr), name, IH_NMLEN);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Ensure the copied string is null terminated by always setting the final
byte to 0. Shorten the strncpy to IH_NMLEN-1 as we will always overwrite
the last byte.

We can't use strlcpy as this is code is built on the host as well as the
target.

Fixes: b97a2a0a21f2 ("[new uImage] Define a API for image handling operations")
Signed-off-by: Joel Stanley <joel at jms.id.au>
---
 include/image.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/image.h b/include/image.h
index e4c6a50b885f..665b2278b7fb 100644
--- a/include/image.h
+++ b/include/image.h
@@ -776,7 +776,10 @@ image_set_hdr_b(comp)		/* image_set_comp */
 
 static inline void image_set_name(image_header_t *hdr, const char *name)
 {
-	strncpy(image_get_name(hdr), name, IH_NMLEN);
+	char *hdr_name = image_get_name(hdr);
+
+	strncpy(hdr_name, name, IH_NMLEN - 1);
+	hdr_name[IH_NMLEN - 1] = '\0';
 }
 
 int image_check_hcrc(const image_header_t *hdr);
-- 
2.35.1