Make local copy of the response, otherwise backend might modify it while frontend is already processing it - leading to time of check / time of use issue.
This is complementary to XSA155.
Cc: stable@vger.kernel.org Signed-off-by: Marek Marczykowski-Górecki marmarek@invisiblethingslab.com --- drivers/net/xen-netfront.c | 51 +++++++++++++++++++-------------------- 1 file changed, 25 insertions(+), 26 deletions(-)
diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c index 4dd0668..dc99763 100644 --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -387,13 +387,13 @@ static void xennet_tx_buf_gc(struct netfront_queue *queue) rmb(); /* Ensure we see responses up to 'rp'. */
for (cons = queue->tx.rsp_cons; cons != prod; cons++) { - struct xen_netif_tx_response *txrsp; + struct xen_netif_tx_response txrsp;
- txrsp = RING_GET_RESPONSE(&queue->tx, cons); - if (txrsp->status == XEN_NETIF_RSP_NULL) + RING_COPY_RESPONSE(&queue->tx, cons, &txrsp); + if (txrsp.status == XEN_NETIF_RSP_NULL) continue;
- id = txrsp->id; + id = txrsp.id; skb = queue->tx_skbs[id].skb; if (unlikely(gnttab_query_foreign_access( queue->grant_tx_ref[id]) != 0)) { @@ -741,7 +741,7 @@ static int xennet_get_extras(struct netfront_queue *queue, RING_IDX rp)
{ - struct xen_netif_extra_info *extra; + struct xen_netif_extra_info extra; struct device *dev = &queue->info->netdev->dev; RING_IDX cons = queue->rx.rsp_cons; int err = 0; @@ -757,24 +757,23 @@ static int xennet_get_extras(struct netfront_queue *queue, break; }
- extra = (struct xen_netif_extra_info *) - RING_GET_RESPONSE(&queue->rx, ++cons); + RING_COPY_RESPONSE(&queue->rx, ++cons, &extra);
- if (unlikely(!extra->type || - extra->type >= XEN_NETIF_EXTRA_TYPE_MAX)) { + if (unlikely(!extra.type || + extra.type >= XEN_NETIF_EXTRA_TYPE_MAX)) { if (net_ratelimit()) dev_warn(dev, "Invalid extra type: %d\n", - extra->type); + extra.type); err = -EINVAL; } else { - memcpy(&extras[extra->type - 1], extra, - sizeof(*extra)); + memcpy(&extras[extra.type - 1], &extra, + sizeof(extra)); }
skb = xennet_get_rx_skb(queue, cons); ref = xennet_get_rx_ref(queue, cons); xennet_move_rx_slot(queue, skb, ref); - } while (extra->flags & XEN_NETIF_EXTRA_FLAG_MORE); + } while (extra.flags & XEN_NETIF_EXTRA_FLAG_MORE);
queue->rx.rsp_cons = cons; return err; @@ -784,28 +783,28 @@ static int xennet_get_responses(struct netfront_queue *queue, struct netfront_rx_info *rinfo, RING_IDX rp, struct sk_buff_head *list) { - struct xen_netif_rx_response *rx = &rinfo->rx; + struct xen_netif_rx_response rx = rinfo->rx; struct xen_netif_extra_info *extras = rinfo->extras; struct device *dev = &queue->info->netdev->dev; RING_IDX cons = queue->rx.rsp_cons; struct sk_buff *skb = xennet_get_rx_skb(queue, cons); grant_ref_t ref = xennet_get_rx_ref(queue, cons); - int max = MAX_SKB_FRAGS + (rx->status <= RX_COPY_THRESHOLD); + int max = MAX_SKB_FRAGS + (rx.status <= RX_COPY_THRESHOLD); int slots = 1; int err = 0; unsigned long ret;
- if (rx->flags & XEN_NETRXF_extra_info) { + if (rx.flags & XEN_NETRXF_extra_info) { err = xennet_get_extras(queue, extras, rp); cons = queue->rx.rsp_cons; }
for (;;) { - if (unlikely(rx->status < 0 || - rx->offset + rx->status > XEN_PAGE_SIZE)) { + if (unlikely(rx.status < 0 || + rx.offset + rx.status > XEN_PAGE_SIZE)) { if (net_ratelimit()) dev_warn(dev, "rx->offset: %u, size: %d\n", - rx->offset, rx->status); + rx.offset, rx.status); xennet_move_rx_slot(queue, skb, ref); err = -EINVAL; goto next; @@ -819,7 +818,7 @@ static int xennet_get_responses(struct netfront_queue *queue, if (ref == GRANT_INVALID_REF) { if (net_ratelimit()) dev_warn(dev, "Bad rx response id %d.\n", - rx->id); + rx.id); err = -EINVAL; goto next; } @@ -832,7 +831,7 @@ static int xennet_get_responses(struct netfront_queue *queue, __skb_queue_tail(list, skb);
next: - if (!(rx->flags & XEN_NETRXF_more_data)) + if (!(rx.flags & XEN_NETRXF_more_data)) break;
if (cons + slots == rp) { @@ -842,7 +841,7 @@ static int xennet_get_responses(struct netfront_queue *queue, break; }
- rx = RING_GET_RESPONSE(&queue->rx, cons + slots); + RING_COPY_RESPONSE(&queue->rx, cons + slots, &rx); skb = xennet_get_rx_skb(queue, cons + slots); ref = xennet_get_rx_ref(queue, cons + slots); slots++; @@ -898,9 +897,9 @@ static RING_IDX xennet_fill_frags(struct netfront_queue *queue, struct sk_buff *nskb;
while ((nskb = __skb_dequeue(list))) { - struct xen_netif_rx_response *rx = - RING_GET_RESPONSE(&queue->rx, ++cons); + struct xen_netif_rx_response rx; skb_frag_t *nfrag = &skb_shinfo(nskb)->frags[0]; + RING_COPY_RESPONSE(&queue->rx, ++cons, &rx);
if (shinfo->nr_frags == MAX_SKB_FRAGS) { unsigned int pull_to = NETFRONT_SKB_CB(skb)->pull_to; @@ -911,7 +910,7 @@ static RING_IDX xennet_fill_frags(struct netfront_queue *queue, BUG_ON(shinfo->nr_frags >= MAX_SKB_FRAGS);
skb_add_rx_frag(skb, shinfo->nr_frags, skb_frag_page(nfrag), - rx->offset, rx->status, PAGE_SIZE); + rx.offset, rx.status, PAGE_SIZE);
skb_shinfo(nskb)->nr_frags = 0; kfree_skb(nskb); @@ -1007,7 +1006,7 @@ static int xennet_poll(struct napi_struct *napi, int budget) i = queue->rx.rsp_cons; work_done = 0; while ((i != rp) && (work_done < budget)) { - memcpy(rx, RING_GET_RESPONSE(&queue->rx, i), sizeof(*rx)); + RING_COPY_RESPONSE(&queue->rx, i, rx); memset(extras, 0, sizeof(rinfo.extras));
err = xennet_get_responses(queue, &rinfo, rp, &tmpq);