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List:       linux-hardening
Subject:    Re: [PATCH] lsm: Add a __counted_by() annotation to lsm_ctx.ctx
From:       Paul Moore <paul () paul-moore ! com>
Date:       2023-12-21 22:34:21
Message-ID: CAHC9VhRwUJkJJVnytxbME4ycmd3BuoLhr-V6xjFWau7eQxeGiw () mail ! gmail ! com
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On Thu, Dec 21, 2023 at 3:39 PM Mark Brown <broonie@kernel.org> wrote:
>
> The ctx in struct lsm_ctx is an array of size ctx_len, tell the compiler
> about this using __counted_by() where supported to improve the ability to
> detect overflow issues.
>
> Reported-by: Aishwarya TCV <aishwarya.tcv@arm.com>
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
>  include/uapi/linux/lsm.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/lsm.h b/include/uapi/linux/lsm.h
> index f0386880a78e..4150333d224f 100644
> --- a/include/uapi/linux/lsm.h
> +++ b/include/uapi/linux/lsm.h
> @@ -36,7 +36,7 @@ struct lsm_ctx {
>         __u64 flags;
>         __u64 len;
>         __u64 ctx_len;
> -       __u8 ctx[];
> +       __u8 ctx[] __counted_by(ctx_len);
>  };

We also now need to include stddef.h in lsm.h for the __counted_by() macro, yes?

-- 
paul-moore.com

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