Re: [RFC: 2.6 patch] hostap_80211_rx(): fix a use-after-free

[Alexey Dobriyan]

On Mon, Nov 06, 2006 at 03:21:48PM +0100, Adrian Bunk wrote:
> This patch fixes a use-after-free for "skb" spotted by the Coverity
> checker.

> --- linux-2.6/drivers/net/wireless/hostap/hostap_80211_rx.c.old
> +++ linux-2.6/drivers/net/wireless/hostap/hostap_80211_rx.c
> @@ -1004,10 +1004,10 @@ void hostap_80211_rx(struct net_device *
>  			if (local->hostapd && local->apdev) {
>  				/* Send IEEE 802.1X frames to the user
>  				 * space daemon for processing */
> -				prism2_rx_80211(local->apdev, skb, rx_stats,
> -						PRISM2_RX_MGMT);
>  				local->apdevstats.rx_packets++;
>  				local->apdevstats.rx_bytes += skb->len;
> +				prism2_rx_80211(local->apdev, skb, rx_stats,
> +						PRISM2_RX_MGMT);
>  				goto rx_exit;

Network drivers set rx_packets and rx_bytes after netif_rx. And last_rx,
too. The trick seems to be to use pkt_len variable.

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