linux-kernel - Re: [PATCH v3 09/12] binfmt_flat: use clear_user() rather than memset() to clear .bss

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Date:	Wed, 20 Jul 2016 17:15:15 +1000
From:	Greg Ungerer <gerg@...ux-m68k.org>
To:	Nicolas Pitre <nicolas.pitre@...aro.org>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	Alexander Viro <viro@...iv.linux.org.uk>,
	David Howells <dhowells@...hat.com>
Subject: Re: [PATCH v3 09/12] binfmt_flat: use clear_user() rather than
 memset() to clear .bss

On 20/07/16 14:20, Nicolas Pitre wrote:
> This is needed on systems with a MMU.
> 
> Signed-off-by: Nicolas Pitre <nico@...aro.org>
> Reviewed-by: Greg Ungerer <gerg@...ux-m68k.org>
> ---
>  fs/binfmt_flat.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
> index 28fc272d9a..0d89830f76 100644
> --- a/fs/binfmt_flat.c
> +++ b/fs/binfmt_flat.c
> @@ -798,10 +798,11 @@ static int load_flat_file(struct linux_binprm * bprm,
>  	flush_icache_range(start_code, end_code);
>  
>  	/* zero the BSS,  BRK and stack areas */
> -	memset((void*)(datapos + data_len), 0, bss_len + 
> +	if (clear_user((void __user *)(datapos + data_len), bss_len + 

nit: this adds a trailing white space                                ^
(Yes, the memset did have this before as well)

Regards
Greg


>  			(memp + memp_size - stack_len -		/* end brk */
>  			libinfo->lib_list[id].start_brk) +	/* start brk */
> -			stack_len);
> +			stack_len))
> +		return -EFAULT;
>  
>  	return 0;
>  err:
>