vboxsf: Add __nonstring annotations for unterminated strings

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.

This effectively reverts the change in 4e7487245abc ("vboxsf: fix building with GCC 15"), to add the annotation that has other uses (i.e. warning if the string is ever used with C string APIs).

Link https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117178 [1]

Cc Hans de Goede <[email protected]>

Cc Brahmajit Das <[email protected]>

Cc Christian Brauner <[email protected]>

Cc [email protected]

Signed-off-by Kees Cook <[email protected]>

---
 fs/vboxsf/super.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

fs/vboxsf/super.c +1 -2

index 1d94bb784108..0bc96ab6580b 100644
@@ -21,8 +21,7 @@
 
 #define VBOXSF_SUPER_MAGIC 0x786f4256 /* 'VBox' little endian */
 
-static const unsigned char VBSF_MOUNT_SIGNATURE[4] = { '\000', '\377', '\376',
-						       '\375' };
+static const unsigned char VBSF_MOUNT_SIGNATURE[4] __nonstring = "\000\377\376\375";
 
 static int follow_symlinks;
 module_param(follow_symlinks, int, 0444);

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.

This effectively reverts the change in 4e7487245abc ("vboxsf: fix building with GCC 15"), to add the annotation that has other uses (i.e. warning if the string is ever used with C string APIs).

[...]