[PATCH] xen/netback: Reset nr_frags before freeing skb

[Ross Lagerwall]

At this point nr_frags has been incremented but the frag does not yet
have a page assigned so freeing the skb results in a crash. Reset
nr_frags before freeing the skb to prevent this.

Signed-off-by: Ross Lagerwall <ross.lagerw...@citrix.com>
---
 drivers/net/xen-netback/netback.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/xen-netback/netback.c 
b/drivers/net/xen-netback/netback.c
index 1d9940d4e8c7..c9262ffeefe4 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -925,6 +925,7 @@ static void xenvif_tx_build_gops(struct xenvif_queue *queue,
                        skb_shinfo(skb)->nr_frags = MAX_SKB_FRAGS;
                        nskb = xenvif_alloc_skb(0);
                        if (unlikely(nskb == NULL)) {
+                               skb_shinfo(skb)->nr_frags = 0;
                                kfree_skb(skb);
                                xenvif_tx_err(queue, &txreq, extra_count, idx);
                                if (net_ratelimit())
@@ -940,6 +941,7 @@ static void xenvif_tx_build_gops(struct xenvif_queue *queue,
 
                        if (xenvif_set_skb_gso(queue->vif, skb, gso)) {
                                /* Failure in xenvif_set_skb_gso is fatal. */
+                               skb_shinfo(skb)->nr_frags = 0;
                                kfree_skb(skb);
                                kfree_skb(nskb);
                                break;
-- 
2.17.2