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From: Daniel Micay <danielmicay@gmail.com>
To: Kees Cook <keescook@chromium.org>, linux-kernel@vger.kernel.org
Cc: kexec@lists.infradead.org, Eric Biederman <ebiederm@xmission.com>
Subject: Re: [PATCH] kexec_file: Adjust type of kexec_purgatory
Date: Tue, 09 May 2017 19:13:45 -0400	[thread overview]
Message-ID: <1494371625.7678.3.camel@gmail.com> (raw)
In-Reply-To: <20170509230639.GA132135@beast>

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?

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WARNING: multiple messages have this Message-ID (diff)
From: Daniel Micay <danielmicay@gmail.com>
To: Kees Cook <keescook@chromium.org>, linux-kernel@vger.kernel.org
Cc: Eric Biederman <ebiederm@xmission.com>, kexec@lists.infradead.org
Subject: Re: [PATCH] kexec_file: Adjust type of kexec_purgatory
Date: Tue, 09 May 2017 19:13:45 -0400	[thread overview]
Message-ID: <1494371625.7678.3.camel@gmail.com> (raw)
In-Reply-To: <20170509230639.GA132135@beast>

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?

  reply	other threads:[~2017-05-09 23:14 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-09 23:06 [PATCH] kexec_file: Adjust type of kexec_purgatory Kees Cook
2017-05-09 23:06 ` Kees Cook
2017-05-09 23:13 ` Daniel Micay [this message]
2017-05-09 23:13   ` Daniel Micay
2017-05-09 23:22   ` Kees Cook
2017-05-09 23:22     ` Kees Cook
2017-05-10  0:15     ` Eric W. Biederman
2017-05-10  0:15       ` Eric W. Biederman
2017-05-10 19:54       ` Kees Cook
2017-05-10 19:54         ` Kees Cook

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