Re: [PATCH v4] [next] dlm: replace one-element array with fixed size array

From: Kees Cook
Date: Tue Oct 11 2022 - 16:06:52 EST


On Wed, Oct 12, 2022 at 09:04:15AM +1300, Paulo Miguel Almeida wrote:
> One-element arrays are deprecated. So, replace one-element array with
> fixed size array member in struct dlm_ls, and refactor the rest of the
> code, accordingly.
>
> Link: https://github.com/KSPP/linux/issues/79
> Link: https://github.com/KSPP/linux/issues/228
> Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836
> Link: https://lore.kernel.org/lkml/Y0W5jkiXUkpNl4ap@xxxxxxxxxxxxxxx/
>
> Signed-off-by: Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@xxxxxxxxx>
> ---
> Changelog:
>
> v4: resend patch using the right version number. Req: Gustavo Silva
> v3: replace one-element array with a fixed size array. Req: Kees Cook
> v2: patch resent as I had an issue with a <CRLF> char in my mail client
> v1: https://lore.kernel.org/lkml/Y0ICbf8tCtXMn+W0@xxxxxxxxxxxxxxx/
> ---
> fs/dlm/dlm_internal.h | 2 +-
> fs/dlm/lockspace.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
> index e34c3d2639a5..94fadb619ba0 100644
> --- a/fs/dlm/dlm_internal.h
> +++ b/fs/dlm/dlm_internal.h
> @@ -670,7 +670,7 @@ struct dlm_ls {
> void *ls_ops_arg;
>
> int ls_namelen;
> - char ls_name[1];
> + char ls_name[DLM_LOCKSPACE_LEN + 1];
> };
>
> /*
> diff --git a/fs/dlm/lockspace.c b/fs/dlm/lockspace.c
> index bae050df7abf..23de0d47cbc1 100644
> --- a/fs/dlm/lockspace.c
> +++ b/fs/dlm/lockspace.c
> @@ -473,7 +473,7 @@ static int new_lockspace(const char *name, const char *cluster,
>
> error = -ENOMEM;
>
> - ls = kzalloc(sizeof(struct dlm_ls) + namelen, GFP_NOFS);
> + ls = kzalloc(sizeof(struct dlm_ls), GFP_NOFS);
^^^^^^^^^^^^^^^^^^^^
I think you forgot the suggestion Gustavo had here. :) Preferred style would
be:
sizeof(*ls)

--
Kees Cook