linux-kernel - Re: [PATCH v3 01/19] x86, kaslr: Remove not needed parameter for choose_kernel

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Date:	Mon, 7 Mar 2016 14:28:49 -0800
From:	Kees Cook <keescook@...omium.org>
To:	Baoquan He <bhe@...hat.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Yinghai Lu <yinghai@...nel.org>,
	"H. Peter Anvin" <hpa@...or.com>, Vivek Goyal <vgoyal@...hat.com>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Andy Lutomirski <luto@...nel.org>, lasse.collin@...aani.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dave Young <dyoung@...hat.com>
Subject: Re: [PATCH v3 01/19] x86, kaslr: Remove not needed parameter for choose_kernel_location

On Fri, Mar 4, 2016 at 8:24 AM, Baoquan He <bhe@...hat.com> wrote:
> From: Yinghai Lu <yinghai@...nel.org>
>
> real_mode is global variable, so we do not need to pass it around.
>
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>

Cool, this makes things cleaner.

Acked-by: Kees Cook <keescook@...omium.org>

-Kees

> ---
>  arch/x86/boot/compressed/aslr.c | 5 ++---
>  arch/x86/boot/compressed/misc.c | 2 +-
>  arch/x86/boot/compressed/misc.h | 6 ++----
>  3 files changed, 5 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c
> index 6a9b96b..622aa88 100644
> --- a/arch/x86/boot/compressed/aslr.c
> +++ b/arch/x86/boot/compressed/aslr.c
> @@ -295,8 +295,7 @@ static unsigned long find_random_addr(unsigned long minimum,
>         return slots_fetch_random();
>  }
>
> -unsigned char *choose_kernel_location(struct boot_params *boot_params,
> -                                     unsigned char *input,
> +unsigned char *choose_kernel_location(unsigned char *input,
>                                       unsigned long input_size,
>                                       unsigned char *output,
>                                       unsigned long output_size)
> @@ -316,7 +315,7 @@ unsigned char *choose_kernel_location(struct boot_params *boot_params,
>         }
>  #endif
>
> -       boot_params->hdr.loadflags |= KASLR_FLAG;
> +       real_mode->hdr.loadflags |= KASLR_FLAG;
>
>         /* Record the various known unsafe memory ranges. */
>         mem_avoid_init((unsigned long)input, input_size,
> diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
> index 79dac17..f35ad9e 100644
> --- a/arch/x86/boot/compressed/misc.c
> +++ b/arch/x86/boot/compressed/misc.c
> @@ -428,7 +428,7 @@ asmlinkage __visible void *decompress_kernel(void *rmode, memptr heap,
>          * the entire decompressed kernel plus relocation table, or the
>          * entire decompressed kernel plus .bss and .brk sections.
>          */
> -       output = choose_kernel_location(real_mode, input_data, input_len, output,
> +       output = choose_kernel_location(input_data, input_len, output,
>                                         output_len > run_size ? output_len
>                                                               : run_size);
>
> diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
> index 3783dc3..dcf01c2 100644
> --- a/arch/x86/boot/compressed/misc.h
> +++ b/arch/x86/boot/compressed/misc.h
> @@ -67,8 +67,7 @@ int cmdline_find_option_bool(const char *option);
>
>  #if CONFIG_RANDOMIZE_BASE
>  /* aslr.c */
> -unsigned char *choose_kernel_location(struct boot_params *boot_params,
> -                                     unsigned char *input,
> +unsigned char *choose_kernel_location(unsigned char *input,
>                                       unsigned long input_size,
>                                       unsigned char *output,
>                                       unsigned long output_size);
> @@ -76,8 +75,7 @@ unsigned char *choose_kernel_location(struct boot_params *boot_params,
>  bool has_cpuflag(int flag);
>  #else
>  static inline
> -unsigned char *choose_kernel_location(struct boot_params *boot_params,
> -                                     unsigned char *input,
> +unsigned char *choose_kernel_location(unsigned char *input,
>                                       unsigned long input_size,
>                                       unsigned char *output,
>                                       unsigned long output_size)
> --
> 2.5.0
>



-- 
Kees Cook
Chrome OS & Brillo Security