Re: [PATCH] kexec_file: Adjust type of kexec_purgatory

From	Daniel Micay <danielmicay@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] kexec_file: Adjust type of kexec_purgatory
Date	2017-05-10 01:20 +0200
Message-ID	<tFmA9-5P-9@gated-at.bofh.it> (permalink)
References	<tFmqu-8sO-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Tue, 2017-05-09 at 16:06 -0700, Kees Cook wrote:
> Defining kexec_purgatory as a zero-length char array upsets compile
> time size checking. Since this is entirely runtime sized, switch
> this to void *. This silences the warning generated by the future
> CONFIG_FORTIFY_SOURCE, which did not like the memcmp() of a "0 byte"
> array.
> 
> Cc: Daniel Micay <danielmicay@gmail.com>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  kernel/kexec_file.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index b118735fea9d..bc86f85f1329 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -30,7 +30,7 @@
>   * Declare these symbols weak so that if architecture provides a
> purgatory,
>   * these will be overridden.
>   */
> -char __weak kexec_purgatory[0];
> +void * __weak kexec_purgatory;
>  size_t __weak kexec_purgatory_size = 0;
>  
>  static int kexec_calculate_store_digests(struct kimage *image);
> -- 
> 2.7.4

It seems more correct to use char `char __weak kexec_purgatory[]`,
otherwise isn't __builtin_object_size ending up as 8, which is still
wrong?

Thread

[PATCH] kexec_file: Adjust type of kexec_purgatory Kees Cook <keescook@chromium.org> - 2017-05-10 01:10 +0200
  Re: [PATCH] kexec_file: Adjust type of kexec_purgatory Daniel Micay <danielmicay@gmail.com> - 2017-05-10 01:20 +0200
    Re: [PATCH] kexec_file: Adjust type of kexec_purgatory Kees Cook <keescook@chromium.org> - 2017-05-10 01:30 +0200
      Re: [PATCH] kexec_file: Adjust type of kexec_purgatory ebiederm@xmission.com (Eric W. Biederman) - 2017-05-10 02:30 +0200
        Re: [PATCH] kexec_file: Adjust type of kexec_purgatory Kees Cook <keescook@chromium.org> - 2017-05-10 22:00 +0200

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