On Thu, Jul 17, 2014 at 08:09:50PM +0100, Zoltan Kiss wrote:
> When the grant operations failed, the skb is freed up eventually, and it tries
> to release the frags, if there is any. For the main skb nr_frags is set to 0
> to
> avoid this, but on the frag_list it iterates through the frags array, and
> tries
> to call put_page on the page pointer which contains garbage at that time.
>
> Signed-off-by: Zoltan Kiss <zoltan.k...@citrix.com>
> Reported-by: Armin Zentai <armin.zen...@ezit.hu>
> Cc: net...@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: xen-de...@lists.xenproject.org
> ---
> diff --git a/drivers/net/xen-netback/netback.c
> b/drivers/net/xen-netback/netback.c
> index 604ff71..e9ffb05 100644
> --- a/drivers/net/xen-netback/netback.c
> +++ b/drivers/net/xen-netback/netback.c
> @@ -1522,6 +1522,11 @@ static int xenvif_tx_submit(struct xenvif_queue *queue)
> /* Check the remap error code. */
> if (unlikely(xenvif_tx_check_gop(queue, skb, &gop_map,
> &gop_copy))) {
It's worth adding a comment here saying that all those pages have been
freed in xenvif_tx_check_gop so that we don't leak any page even if we
manually set nr_frags to 0.
Wei.
> skb_shinfo(skb)->nr_frags = 0;
> + if (skb_has_frag_list(skb)) {
> + struct sk_buff *nskb =
> + skb_shinfo(skb)->frag_list;
> + skb_shinfo(nskb)->nr_frags = 0;
> + }
> kfree_skb(skb);
> continue;
> }
--
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