xen/netback: free already allocated memory on failure in xen_netbk_get_requests

[ Upstream commit 4cc7c1cb7b11b6f3515bd9075527576a1eecc4aa ]

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index d6c235990374823869b874589bde5f23d9d535ef..a14b3a2a2f1d4db7e68d1f48a1fd0aa99366b0d4 100644 (file)
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -950,7 +950,7 @@ static struct gnttab_copy *xen_netbk_get_requests(struct xen_netbk *netbk,
                pending_idx = netbk->pending_ring[index];
                page = xen_netbk_alloc_page(netbk, skb, pending_idx);
                if (!page)
-                       return NULL;
+                       goto err;
 
                netbk->mmap_pages[pending_idx] = page;
 
@@ -974,6 +974,17 @@ static struct gnttab_copy *xen_netbk_get_requests(struct xen_netbk *netbk,
        }
 
        return gop;
+err:
+       /* Unwind, freeing all pages and sending error responses. */
+       while (i-- > start) {
+               xen_netbk_idx_release(netbk, frag_get_pending_idx(&frags[i]),
+                                     XEN_NETIF_RSP_ERROR);
+       }
+       /* The head too, if necessary. */
+       if (start)
+               xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_ERROR);
+
+       return NULL;
 }
 
 static int xen_netbk_tx_check_gop(struct xen_netbk *netbk,