Subject: Re: [PATCH] eexpress: Read buffer overflow

From: Jarek Poplawski <[email-masked]>
Date: Sun, 26 Jul 2009 22:16:38 +0200

Roel Kluin wrote, On 07/25/2009 09:50 PM:

> start_code is 69 words, but the code always writes a multiple of 16 words,
> so the last 11 words written are outside the array.
> 
> Signed-off-by: Roel Kluin <[email-masked]>
> ---
> This was observed using Parfait http://research.sun.com/projects/parfait/
> 
> diff --git a/drivers/net/eexpress.c b/drivers/net/eexpress.c
> index 1686dca..e304abb 100644
> --- a/drivers/net/eexpress.c
> +++ b/drivers/net/eexpress.c
> @@ -1474,15 +1474,14 @@ static void eexp_hw_init586(struct net_device *dev)
>  	outw(0x0000, ioaddr + 0x800c);
>  	outw(0x0000, ioaddr + 0x800e);
>  
> -	for (i = 0; i < (sizeof(start_code)); i+=32) {
> -		int j;
> -		outw(i, ioaddr + SM_PTR);
> -		for (j = 0; j < 16; j+=2)
> -			outw(start_code[(i+j)/2],
> -			     ioaddr+0x4000+j);
> -		for (j = 0; j < 16; j+=2)
> -			outw(start_code[(i+j+16)/2],
> -			     ioaddr+0x8000+j);

(max) i = 64, (max) j = 14, (64+14+16)/2 = 47 < 69, so it seems to copy
less than its size?

Jarek P.

> +	for (i = 0; i < ARRAY_SIZE(start_code); i += 16) {
> +		int j, jmax;
> +		outw(i * 2, ioaddr + SM_PTR);
> +
> +		jmax = min_t(int, 16, ARRAY_SIZE(start_code) - i);
> +		for (j = 0; j < jmax; j++)
> +			outw(start_code[i + j],
> +			     ioaddr + j * 2 + (j < 8 ? 0x4000 : 0x8000 - 16));
>  	}
>  
>  	/* Do we want promiscuous mode or multicast? */
> --
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