netdev - Re: [PATCH 2.6.24] pasemi_mac: Fix reuse of free'd skb

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Date:	Tue, 04 Dec 2007 14:54:44 -0500
From:	Jeff Garzik <jgarzik@...ox.com>
To:	Olof Johansson <olof@...om.net>
CC:	netdev@...r.kernel.org, linuxppc-dev@...abs.org,
	dwmw2@...radead.org, ranger@...too.org
Subject: Re: [PATCH 2.6.24] pasemi_mac: Fix reuse of free'd skb

Olof Johansson wrote:
> Turns out we're freeing the skb when we detect CRC error, but we're
> not clearing out info->skb. We could either clear it and have the stack
> reallocate it, or just leave it and the rx ring refill code will reuse
> the one that was allocated.
> 
> Reusing a freed skb obviously caused some nasty crashes of various kind,
> as reported by Brent Baude and David Woodhouse.
> 
> 
> Signed-off-by: Olof Johansson <olof@...om.net>
> 
> ---
> 
> Jeff, I'd like to see this in 2.6.24, it's causing some real problems
> out there. It's not needed in the 2.6.25 queue since the other changes
> there have already covered these cases.
> 
> My test network at home is quiet enough to not cause CRC errors, we
> mainly get those during interface bringup before speed is configured.
> 
> diff --git a/drivers/net/pasemi_mac.c b/drivers/net/pasemi_mac.c
> index 09b4fde..6617e24 100644
> --- a/drivers/net/pasemi_mac.c
> +++ b/drivers/net/pasemi_mac.c
> @@ -586,7 +586,7 @@ static int pasemi_mac_clean_rx(struct pasemi_mac *mac, int limit)
>  			/* CRC error flagged */
>  			mac->netdev->stats.rx_errors++;
>  			mac->netdev->stats.rx_crc_errors++;
> -			dev_kfree_skb_irq(skb);
> +			/* No need to free skb, it'll be reused */
>  			goto next;

applied #upstream-fixes


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