3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Juergen Gross <jgr...@suse.com>

commit d472b3a6cf63cd31cae1ed61930f07e6cd6671b5 upstream.

skb_shinfo() can change when calling __pskb_pull_tail(): Don't cache
its return value.

Cc: sta...@vger.kernel.org
Signed-off-by: Juergen Gross <jgr...@suse.com>
Reviewed-by: Wei Liu <wei.l...@citrix.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/net/xen-netfront.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -903,7 +903,6 @@ static RING_IDX xennet_fill_frags(struct
                                  struct sk_buff *skb,
                                  struct sk_buff_head *list)
 {
-       struct skb_shared_info *shinfo = skb_shinfo(skb);
        RING_IDX cons = queue->rx.rsp_cons;
        struct sk_buff *nskb;
 
@@ -912,15 +911,16 @@ static RING_IDX xennet_fill_frags(struct
                        RING_GET_RESPONSE(&queue->rx, ++cons);
                skb_frag_t *nfrag = &skb_shinfo(nskb)->frags[0];
 
-               if (shinfo->nr_frags == MAX_SKB_FRAGS) {
+               if (skb_shinfo(skb)->nr_frags == MAX_SKB_FRAGS) {
                        unsigned int pull_to = NETFRONT_SKB_CB(skb)->pull_to;
 
                        BUG_ON(pull_to <= skb_headlen(skb));
                        __pskb_pull_tail(skb, pull_to - skb_headlen(skb));
                }
-               BUG_ON(shinfo->nr_frags >= MAX_SKB_FRAGS);
+               BUG_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS);
 
-               skb_add_rx_frag(skb, shinfo->nr_frags, skb_frag_page(nfrag),
+               skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
+                               skb_frag_page(nfrag),
                                rx->offset, rx->status, PAGE_SIZE);
 
                skb_shinfo(nskb)->nr_frags = 0;


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