[PATCH AUTOSEL 5.15 5/6] xen/mcelog: Add __nonstring annotations for unterminated strings

[Sasha Levin <sashal@xxxxxxxxxx>]

From: Kees Cook <kees@xxxxxxxxxx>

[ Upstream commit 1c3dfc7c6b0f551fdca3f7c1f1e4c73be8adb17d ]

When a character array without a terminating NUL character has a static
initializer, GCC 15's -Wunterminated-string-initialization will only
warn if the array lacks the "nonstring" attribute[1]. Mark the arrays
with __nonstring to and correctly identify the char array as "not a C
string" and thereby eliminate the warning.

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117178 [1]
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <kees@xxxxxxxxxx>
Acked-by: Juergen Gross <jgross@xxxxxxxx>
Message-ID: <20250310222234.work.473-kees@xxxxxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 include/xen/interface/xen-mca.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/xen/interface/xen-mca.h b/include/xen/interface/xen-mca.h
index 7483a78d24251..20a3b320d1a58 100644
--- a/include/xen/interface/xen-mca.h
+++ b/include/xen/interface/xen-mca.h
@@ -371,7 +371,7 @@ struct xen_mce {
 #define XEN_MCE_LOG_LEN 32
 
 struct xen_mce_log {
-       char signature[12]; /* "MACHINECHECK" */
+       char signature[12] __nonstring; /* "MACHINECHECK" */
        unsigned len;       /* = XEN_MCE_LOG_LEN */
        unsigned next;
        unsigned flags;
-- 
2.39.5