[Xen-devel] [PATCH v2 3/4] xen/netback: free already allocated memory on failure in xen_netbk_get_requests

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 3.0+
---
v2: s/reponses/responses/ (blp) & fixup block comment style (DaveM)
---
 drivers/net/xen-netback/netback.c |   13 ++++++++++++-
 1 files changed, 12 insertions(+), 1 deletions(-)

diff --git a/drivers/net/xen-netback/netback.c 
b/drivers/net/xen-netback/netback.c
index bf692df..dcb2d4d 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -978,7 +978,7 @@ 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;
 
                gop->source.u.ref = txp->gref;
                gop->source.domid = vif->domid;
@@ -1000,6 +1000,17 @@ 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,
-- 
1.7.2.5


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