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authorWei Liu <wei.liu2@citrix.com>2013-04-22 02:20:43 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-06-07 12:53:36 -0700
commit7ba65651e0c75fa221d8ca41aec99843b4055304 (patch)
tree22071f3fa9c8c6d519507854e59db2a15ad25bc6
parentc34e3784b94f9eef8860bb142ca56fddb3c5951f (diff)
downloadvexpress-lsk-7ba65651e0c75fa221d8ca41aec99843b4055304.tar.gz
xen-netback: don't disconnect frontend when seeing oversize packet
commit 03393fd5cc2b6cdeec32b704ecba64dbb0feae3c upstream. Some frontend drivers are sending packets > 64 KiB in length. This length overflows the length field in the first slot making the following slots have an invalid length. Turn this error back into a non-fatal error by dropping the packet. To avoid having the following slots having fatal errors, consume all slots in the packet. This does not reopen the security hole in XSA-39 as if the packet as an invalid number of slots it will still hit fatal error case. Signed-off-by: David Vrabel <david.vrabel@citrix.com> Signed-off-by: Wei Liu <wei.liu2@citrix.com> Acked-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/net/xen-netback/netback.c22
1 files changed, 16 insertions, 6 deletions
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 2b50c6736bd..b74bc4faa45 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -975,12 +975,22 @@ static int netbk_count_requests(struct xenvif *vif,
memcpy(txp, RING_GET_REQUEST(&vif->tx, cons + slots),
sizeof(*txp));
- if (txp->size > first->size) {
- netdev_err(vif->dev,
- "Invalid tx request, slot size %u > remaining size %u\n",
- txp->size, first->size);
- netbk_fatal_tx_err(vif);
- return -EIO;
+
+ /* If the guest submitted a frame >= 64 KiB then
+ * first->size overflowed and following slots will
+ * appear to be larger than the frame.
+ *
+ * This cannot be fatal error as there are buggy
+ * frontends that do this.
+ *
+ * Consume all slots and drop the packet.
+ */
+ if (!drop_err && txp->size > first->size) {
+ if (net_ratelimit())
+ netdev_dbg(vif->dev,
+ "Invalid tx request, slot size %u > remaining size %u\n",
+ txp->size, first->size);
+ drop_err = -EIO;
}
first->size -= txp->size;