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Date: Mon, 30 Apr 2018 23:01:46 +0200
From: Marek Marczykowski-Górecki
<marmarek@...isiblethingslab.com>
To: xen-devel@...ts.xenproject.org
Cc: Marek Marczykowski-Górecki
<marmarek@...isiblethingslab.com>, stable@...r.kernel.org,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Juergen Gross <jgross@...e.com>,
netdev@...r.kernel.org (open list:NETWORKING DRIVERS),
linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 2/6] xen-netfront: copy response out of shared buffer before accessing it
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@...r.kernel.org
Signed-off-by: Marek Marczykowski-Górecki <marmarek@...isiblethingslab.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);
--
git-series 0.9.1
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