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-rw-r--r--main/linux-grsec/xsa39-pvops-0001-xen-netback-shutdown-the-ring-if-it-contains-garbage.patch253
1 files changed, 253 insertions, 0 deletions
diff --git a/main/linux-grsec/xsa39-pvops-0001-xen-netback-shutdown-the-ring-if-it-contains-garbage.patch b/main/linux-grsec/xsa39-pvops-0001-xen-netback-shutdown-the-ring-if-it-contains-garbage.patch
new file mode 100644
index 000000000..3f983028f
--- /dev/null
+++ b/main/linux-grsec/xsa39-pvops-0001-xen-netback-shutdown-the-ring-if-it-contains-garbage.patch
@@ -0,0 +1,253 @@
+From 7dd7ce44593a8c4c715fa665027af8e07245c8cf Mon Sep 17 00:00:00 2001
+From: Ian Campbell <ian.campbell@citrix.com>
+Date: Fri, 11 Jan 2013 14:26:29 +0000
+Subject: [PATCH 1/4] xen/netback: shutdown the ring if it contains garbage.
+
+A buggy or malicious frontend should not be able to confuse netback.
+If we spot anything which is not as it should be then shutdown the
+device and don't try to continue with the ring in a potentially
+hostile state. Well behaved and non-hostile frontends will not be
+penalised.
+
+As well as making the existing checks for such errors fatal also add a
+new check that ensures that there isn't an insane number of requests
+on the ring (i.e. more than would fit in the ring). If the ring
+contains garbage then previously is was possible to loop over this
+insane number, getting an error each time and therefore not generating
+any more pending requests and therefore not exiting the loop in
+xen_netbk_tx_build_gops for an externded period.
+
+Also turn various netdev_dbg calls which no precipitate a fatal error
+into netdev_err, they are rate limited because the device is shutdown
+afterwards.
+
+This fixes at least one known DoS/softlockup of the backend domain.
+
+Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
+Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
+Acked-by: Jan Beulich <JBeulich@suse.com>
+---
+ drivers/net/xen-netback/common.h | 3 ++
+ drivers/net/xen-netback/interface.c | 23 ++++++++-----
+ drivers/net/xen-netback/netback.c | 63 +++++++++++++++++++++++++---------
+ 3 files changed, 63 insertions(+), 26 deletions(-)
+
+diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
+index 94b79c3..9d7f172 100644
+--- a/drivers/net/xen-netback/common.h
++++ b/drivers/net/xen-netback/common.h
+@@ -151,6 +151,9 @@ void xen_netbk_queue_tx_skb(struct xenvif *vif, struct sk_buff *skb);
+ /* Notify xenvif that ring now has space to send an skb to the frontend */
+ void xenvif_notify_tx_completion(struct xenvif *vif);
+
++/* Prevent the device from generating any further traffic. */
++void xenvif_carrier_off(struct xenvif *vif);
++
+ /* Returns number of ring slots required to send an skb to the frontend */
+ unsigned int xen_netbk_count_skb_slots(struct xenvif *vif, struct sk_buff *skb);
+
+diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
+index b7d41f8..b8c5193 100644
+--- a/drivers/net/xen-netback/interface.c
++++ b/drivers/net/xen-netback/interface.c
+@@ -343,17 +343,22 @@ err:
+ return err;
+ }
+
+-void xenvif_disconnect(struct xenvif *vif)
++void xenvif_carrier_off(struct xenvif *vif)
+ {
+ struct net_device *dev = vif->dev;
+- if (netif_carrier_ok(dev)) {
+- rtnl_lock();
+- netif_carrier_off(dev); /* discard queued packets */
+- if (netif_running(dev))
+- xenvif_down(vif);
+- rtnl_unlock();
+- xenvif_put(vif);
+- }
++
++ rtnl_lock();
++ netif_carrier_off(dev); /* discard queued packets */
++ if (netif_running(dev))
++ xenvif_down(vif);
++ rtnl_unlock();
++ xenvif_put(vif);
++}
++
++void xenvif_disconnect(struct xenvif *vif)
++{
++ if (netif_carrier_ok(vif->dev))
++ xenvif_carrier_off(vif);
+
+ atomic_dec(&vif->refcnt);
+ wait_event(vif->waiting_to_free, atomic_read(&vif->refcnt) == 0);
+diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
+index f2d6b78..1a449f9 100644
+--- a/drivers/net/xen-netback/netback.c
++++ b/drivers/net/xen-netback/netback.c
+@@ -888,6 +888,13 @@ static void netbk_tx_err(struct xenvif *vif,
+ xenvif_put(vif);
+ }
+
++static void netbk_fatal_tx_err(struct xenvif *vif)
++{
++ netdev_err(vif->dev, "fatal error; disabling device\n");
++ xenvif_carrier_off(vif);
++ xenvif_put(vif);
++}
++
+ static int netbk_count_requests(struct xenvif *vif,
+ struct xen_netif_tx_request *first,
+ struct xen_netif_tx_request *txp,
+@@ -901,19 +908,22 @@ static int netbk_count_requests(struct xenvif *vif,
+
+ do {
+ if (frags >= work_to_do) {
+- netdev_dbg(vif->dev, "Need more frags\n");
++ netdev_err(vif->dev, "Need more frags\n");
++ netbk_fatal_tx_err(vif);
+ return -frags;
+ }
+
+ if (unlikely(frags >= MAX_SKB_FRAGS)) {
+- netdev_dbg(vif->dev, "Too many frags\n");
++ netdev_err(vif->dev, "Too many frags\n");
++ netbk_fatal_tx_err(vif);
+ return -frags;
+ }
+
+ memcpy(txp, RING_GET_REQUEST(&vif->tx, cons + frags),
+ sizeof(*txp));
+ if (txp->size > first->size) {
+- netdev_dbg(vif->dev, "Frags galore\n");
++ netdev_err(vif->dev, "Frag is bigger than frame.\n");
++ netbk_fatal_tx_err(vif);
+ return -frags;
+ }
+
+@@ -921,8 +931,9 @@ static int netbk_count_requests(struct xenvif *vif,
+ frags++;
+
+ if (unlikely((txp->offset + txp->size) > PAGE_SIZE)) {
+- netdev_dbg(vif->dev, "txp->offset: %x, size: %u\n",
++ netdev_err(vif->dev, "txp->offset: %x, size: %u\n",
+ txp->offset, txp->size);
++ netbk_fatal_tx_err(vif);
+ return -frags;
+ }
+ } while ((txp++)->flags & XEN_NETTXF_more_data);
+@@ -1095,7 +1106,8 @@ static int xen_netbk_get_extras(struct xenvif *vif,
+
+ do {
+ if (unlikely(work_to_do-- <= 0)) {
+- netdev_dbg(vif->dev, "Missing extra info\n");
++ netdev_err(vif->dev, "Missing extra info\n");
++ netbk_fatal_tx_err(vif);
+ return -EBADR;
+ }
+
+@@ -1104,8 +1116,9 @@ static int xen_netbk_get_extras(struct xenvif *vif,
+ if (unlikely(!extra.type ||
+ extra.type >= XEN_NETIF_EXTRA_TYPE_MAX)) {
+ vif->tx.req_cons = ++cons;
+- netdev_dbg(vif->dev,
++ netdev_err(vif->dev,
+ "Invalid extra type: %d\n", extra.type);
++ netbk_fatal_tx_err(vif);
+ return -EINVAL;
+ }
+
+@@ -1121,13 +1134,15 @@ static int netbk_set_skb_gso(struct xenvif *vif,
+ struct xen_netif_extra_info *gso)
+ {
+ if (!gso->u.gso.size) {
+- netdev_dbg(vif->dev, "GSO size must not be zero.\n");
++ netdev_err(vif->dev, "GSO size must not be zero.\n");
++ netbk_fatal_tx_err(vif);
+ return -EINVAL;
+ }
+
+ /* Currently only TCPv4 S.O. is supported. */
+ if (gso->u.gso.type != XEN_NETIF_GSO_TYPE_TCPV4) {
+- netdev_dbg(vif->dev, "Bad GSO type %d.\n", gso->u.gso.type);
++ netdev_err(vif->dev, "Bad GSO type %d.\n", gso->u.gso.type);
++ netbk_fatal_tx_err(vif);
+ return -EINVAL;
+ }
+
+@@ -1264,9 +1279,26 @@ static unsigned xen_netbk_tx_build_gops(struct xen_netbk *netbk)
+
+ /* Get a netif from the list with work to do. */
+ vif = poll_net_schedule_list(netbk);
++ /*
++ * This can sometimes happen because the test of
++ * list_empty(net_schedule_list) at the top of the
++ * loop is unlocked. Just go back and have another
++ * look.
++ */
+ if (!vif)
+ continue;
+
++ if (vif->tx.sring->req_prod - vif->tx.req_cons >
++ XEN_NETIF_TX_RING_SIZE) {
++ netdev_err(vif->dev,
++ "Impossible number of requests. "
++ "req_prod %d, req_cons %d, size %ld\n",
++ vif->tx.sring->req_prod, vif->tx.req_cons,
++ XEN_NETIF_TX_RING_SIZE);
++ netbk_fatal_tx_err(vif);
++ continue;
++ }
++
+ RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, work_to_do);
+ if (!work_to_do) {
+ xenvif_put(vif);
+@@ -1294,17 +1326,14 @@ static unsigned xen_netbk_tx_build_gops(struct xen_netbk *netbk)
+ work_to_do = xen_netbk_get_extras(vif, extras,
+ work_to_do);
+ idx = vif->tx.req_cons;
+- if (unlikely(work_to_do < 0)) {
+- netbk_tx_err(vif, &txreq, idx);
++ if (unlikely(work_to_do < 0))
+ continue;
+- }
+ }
+
+ ret = netbk_count_requests(vif, &txreq, txfrags, work_to_do);
+- if (unlikely(ret < 0)) {
+- netbk_tx_err(vif, &txreq, idx - ret);
++ if (unlikely(ret < 0))
+ continue;
+- }
++
+ idx += ret;
+
+ if (unlikely(txreq.size < ETH_HLEN)) {
+@@ -1316,11 +1345,11 @@ static unsigned xen_netbk_tx_build_gops(struct xen_netbk *netbk)
+
+ /* No crossing a page as the payload mustn't fragment. */
+ if (unlikely((txreq.offset + txreq.size) > PAGE_SIZE)) {
+- netdev_dbg(vif->dev,
++ netdev_err(vif->dev,
+ "txreq.offset: %x, size: %u, end: %lu\n",
+ txreq.offset, txreq.size,
+ (txreq.offset&~PAGE_MASK) + txreq.size);
+- netbk_tx_err(vif, &txreq, idx);
++ netbk_fatal_tx_err(vif);
+ continue;
+ }
+
+@@ -1348,8 +1377,8 @@ static unsigned xen_netbk_tx_build_gops(struct xen_netbk *netbk)
+ gso = &extras[XEN_NETIF_EXTRA_TYPE_GSO - 1];
+
+ if (netbk_set_skb_gso(vif, skb, gso)) {
++ /* Failure in netbk_set_skb_gso is fatal. */
+ kfree_skb(skb);
+- netbk_tx_err(vif, &txreq, idx);
+ continue;
+ }
+ }
+--
+1.7.2.5
+
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