linux-kernel - Re: [PATCH] s390: mmap base does not depend on ADDR_NO

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Message-Id: <20190601105534.GG3600@osiris>
Date:   Sat, 1 Jun 2019 12:55:35 +0200
From:   Heiko Carstens <heiko.carstens@...ibm.com>
To:     Alexandre Ghiti <alex@...ti.fr>
Cc:     Martin Schwidefsky <schwidefsky@...ibm.com>,
        Kees Cook <keescook@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] s390: mmap base does not depend on ADDR_NO_RANDOMIZE
 personality

On Thu, Apr 04, 2019 at 02:19:56AM -0400, Alexandre Ghiti wrote:
> randomize_stack_top() checks for current task flag PF_RANDOMIZE in order
> to use stack randomization and PF_RANDOMIZE is set when
> ADDR_NO_RANDOMIZE is unset, so no need to check for ADDR_NO_RANDOMIZE
> in stack_maxrandom_size.
> 
> Signed-off-by: Alexandre Ghiti <alex@...ti.fr>
> ---
>  arch/s390/mm/mmap.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
> index 687f2a4d3459..5185ed0a0463 100644
> --- a/arch/s390/mm/mmap.c
> +++ b/arch/s390/mm/mmap.c
> @@ -24,8 +24,7 @@ static unsigned long stack_maxrandom_size(void)
>  {
>  	if (!(current->flags & PF_RANDOMIZE))
>  		return 0;
> -	if (current->personality & ADDR_NO_RANDOMIZE)
> -		return 0;
> +
>  	return STACK_RND_MASK << PAGE_SHIFT;

Applied, thanks.