linux-kernel - Re: [PATCH 2/3] mmap: round mmap hint address above mmap_min

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Date:	Sat, 17 Nov 2007 08:42:26 +1100 (EST)
From:	James Morris <jmorris@...ei.org>
To:	Eric Paris <eparis@...hat.com>
cc:	linux-kernel@...r.kernel.org, sds@...ho.nsa.gov,
	selinux@...ho.nsa.gov, alan@...hat.com, chrisw@...hat.com,
	hpa@...or.com, akpm@...ux-foundation.org
Subject: Re: [PATCH 2/3] mmap: round mmap hint address above mmap_min_addr

On Fri, 16 Nov 2007, Eric Paris wrote:

> +#ifdef CONFIG_SECURITY
> +	/*
> +	 * If a hint addr is less than mmap_min_addr change addr to be as
> +	 * low as possible but still greater than mmap_min_addr
> +	 */
> +	if (!(flags & MAP_FIXED) && ((void *)addr != NULL) &&
> +	    (addr < mmap_min_addr))
> +		addr = PAGE_ALIGN(mmap_min_addr);
> +#endif

Please make this a static inline which is optimized away with 
!CONFIG_SECURITY.


> +
>  	error = arch_mmap_check(addr, len, flags);
>  	if (error)
>  		return error;
> diff --git a/mm/nommu.c b/mm/nommu.c
> index 35622c5..ea4d20a 100644
> --- a/mm/nommu.c
> +++ b/mm/nommu.c
> @@ -829,6 +829,16 @@ unsigned long do_mmap_pgoff(struct file *file,
>  	void *result;
>  	int ret;
>  
> +#ifdef CONFIG_SECURITY
> +	/*
> +	 * If a hint addr is less than mmap_min_addr change addr to be as
> +	 * low as possible, but still greater than mmap_min_addr
> +	 */
> +	if (!(flags & MAP_FIXED) && ((void *)addr != NULL) &&
> +	    (addr < mmap_min_addr))
> +		addr = PAGE_ALIGN(mmap_min_addr);
> +#endif
> +
>  	/* decide whether we should attempt the mapping, and if so what sort of
>  	 * mapping */
>  	ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
> 
> 

-- 
James Morris
<jmorris@...ei.org>
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