Re: [PATCH v9 03/27] kallsyms: add static relationship between `KSYM_NAME_LEN{,_BUFFER}`

Kees Cook
2022-08-17T19:40:14Z

On Fri, Aug 05, 2022 at 05:41:48PM +0200, Miguel Ojeda wrote:
> This adds a static assert to ensure `KSYM_NAME_LEN_BUFFER`
> gets updated when `KSYM_NAME_LEN` changes.
>
> The relationship used is one that keeps the new size (512+1)
> close to the original buffer size (500).
>
> Co-developed-by: Boqun Feng <boqun.feng@gmail.com>
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
> ---
> scripts/kallsyms.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
> index f3c5a2623f71..f543b1c4f99f 100644
> --- a/scripts/kallsyms.c
> +++ b/scripts/kallsyms.c
> @@ -33,7 +33,11 @@
> #define KSYM_NAME_LEN 128
>
> /* A substantially bigger size than the current maximum. */
> -#define KSYM_NAME_LEN_BUFFER 499
> +#define KSYM_NAME_LEN_BUFFER 512
> +_Static_assert(
> + KSYM_NAME_LEN_BUFFER == KSYM_NAME_LEN * 4,
> + "Please keep KSYM_NAME_LEN_BUFFER in sync with KSYM_NAME_LEN"
> +);

Why not just make this define:

#define KSYM_NAME_LEN_BUFFER (KSYM_NAME_LEN * 4)

? If there's a good reason not it, please put it in the commit log.

-Kees

--
Kees Cook