[ 29/36] xen/netback: free already allocated memory on failure in xen_netbk_get_requests

[Greg Kroah-Hartman]

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

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


From: Ian Campbell <Ian.Campbell@xxxxxxxxxx>

[ Upstream commit 4cc7c1cb7b11b6f3515bd9075527576a1eecc4aa ]

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/xen-netback/netback.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

--- 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
 		pending_idx = netbk->pending_ring[index];
 		page = xen_netbk_alloc_page(netbk, skb, pending_idx);
 		if (!page)
-			return NULL;
+			goto err;
 
 		gop->source.u.ref = txp->gref;
 		gop->source.domid = vif->domid;
@@ -972,6 +972,17 @@ static struct gnttab_copy *xen_netbk_get
 	}
 
 	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,


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