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Date: Tue, 2 Dec 2008 14:05:37 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: roel kluin <roel.kluin@gmail.com>
Cc: ben-linux@fluff.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sm501: unsigned ptr cannot be negative
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On Sat, 29 Nov 2008 06:49:20 -0500
roel kluin <roel.kluin@gmail.com> wrote:

> unsigned ptr cannot be negative
> 
> Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
> ---
> diff --git a/drivers/video/sm501fb.c b/drivers/video/sm501fb.c
> index f94ae84..dcd9879 100644
> --- a/drivers/video/sm501fb.c
> +++ b/drivers/video/sm501fb.c
> @@ -159,6 +159,9 @@ static int sm501_alloc_mem(struct sm501fb_info *inf, struct sm501_mem *mem,
>  		break;
>  
>  	case SM501_MEMF_PANEL:
> +		if (size > inf->fbmem_len)
> +			return -ENOMEM;
> +
>  		ptr = inf->fbmem_len - size;
>  		fbi = inf->fb[HEAD_CRT];
>  
> @@ -172,9 +175,6 @@ static int sm501_alloc_mem(struct sm501fb_info *inf, struct sm501_mem *mem,
>  		if (fbi && ptr < fbi->fix.smem_len)
>  			return -ENOMEM;
>  
> -		if (ptr < 0)
> -			return -ENOMEM;
> -
>  		break;
>  
>  	case SM501_MEMF_CRT:

Looks OK.

Also this:

	if (ptr > 0)
		ptr &= ~(PAGE_SIZE - 1);

could just be

	ptr = PAGE_ALIGN(ptr);