Re: [PATCH] ntfs3: align struct ATTR_LIST_ENTRY

Randy Dunlap
2023-12-08T00:37:37Z

On 12/7/23 06:28, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> On architectures like i386 that don't enforce natural alignment of u64
> struct members, so the recent change to remove the final 48 bits
> reduced the structure size from 32 to 28 bytes:
>
> include/linux/build_bug.h:78:41: error: static assertion failed: "sizeof(struct ATTR_LIST_ENTRY) == 0x20"
> fs/ntfs3/ntfs.h:530:1: note: in expansion of macro 'static_assert'
> 530 | static_assert(sizeof(struct ATTR_LIST_ENTRY) == 0x20);
> | ^~~~~~~~~~~~~
>
> Add an alignment attribute that makes the structure the same across
> all architectures again.
>
> Fixes: d155617006eb ("fs/ntfs3: Fix detected field-spanning write (size 8) of single field "le->name"")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org> # build-tested

Thanks.

> ---
> fs/ntfs3/ntfs.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/ntfs3/ntfs.h b/fs/ntfs3/ntfs.h
> index c8981429c721..2d409ac94cbb 100644
> --- a/fs/ntfs3/ntfs.h
> +++ b/fs/ntfs3/ntfs.h
> @@ -525,7 +525,7 @@ struct ATTR_LIST_ENTRY {
> __le16 id; // 0x18: struct ATTRIB ID.
> __le16 name[]; // 0x1A: To get real name use name_off.
>
> -}; // sizeof(0x20)
> +} __aligned((8)); // sizeof(0x20)
>
> static_assert(sizeof(struct ATTR_LIST_ENTRY) == 0x20);
>

--
~Randy