Re: [PATCH] fs: Replace offsetof() with struct_size()

From: Jan Kara
Date: Fri Aug 29 2025 - 06:40:22 EST


On Fri 29-08-25 18:03:28, Xichao Zhao wrote:
> When dealing with structures containing flexible arrays, struct_size()
> provides additional compile-time checks compared to offsetof(). This
> enhances code robustness and reduces the risk of potential errors.
>
> Signed-off-by: Xichao Zhao <zhao.xichao@xxxxxxxx>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

Honza

> ---
> fs/namei.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/namei.c b/fs/namei.c
> index 10f7caff7f0f..70a71b1b8abc 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -178,7 +178,7 @@ getname_flags(const char __user *filename, int flags)
> * userland.
> */
> if (unlikely(len == EMBEDDED_NAME_MAX)) {
> - const size_t size = offsetof(struct filename, iname[1]);
> + const size_t size = struct_size(result, iname, 1);
> kname = (char *)result;
>
> /*
> @@ -253,7 +253,7 @@ struct filename *getname_kernel(const char * filename)
> if (len <= EMBEDDED_NAME_MAX) {
> result->name = (char *)result->iname;
> } else if (len <= PATH_MAX) {
> - const size_t size = offsetof(struct filename, iname[1]);
> + const size_t size = struct_size(result, iname, 1);
> struct filename *tmp;
>
> tmp = kmalloc(size, GFP_KERNEL);
> --
> 2.34.1
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR