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-rw-r--r--system/xen/xsa/xsa184-qemut-master.patch43
1 files changed, 43 insertions, 0 deletions
diff --git a/system/xen/xsa/xsa184-qemut-master.patch b/system/xen/xsa/xsa184-qemut-master.patch
new file mode 100644
index 0000000000..d15167f4ac
--- /dev/null
+++ b/system/xen/xsa/xsa184-qemut-master.patch
@@ -0,0 +1,43 @@
+From 17d8c4e47dfb41cb6778520ff2eab7a11fe12dfd Mon Sep 17 00:00:00 2001
+From: P J P <ppandit@redhat.com>
+Date: Tue, 26 Jul 2016 15:31:59 +0100
+Subject: [PATCH] virtio: error out if guest exceeds virtqueue size
+
+A broken or malicious guest can submit more requests than the virtqueue
+size permits.
+
+The guest can submit requests without bothering to wait for completion
+and is therefore not bound by virtqueue size. This requires reusing
+vring descriptors in more than one request, which is incorrect but
+possible. Processing a request allocates a VirtQueueElement and
+therefore causes unbounded memory allocation controlled by the guest.
+
+Exit with an error if the guest provides more requests than the
+virtqueue size permits. This bounds memory allocation and makes the
+buggy guest visible to the user.
+
+Reported-by: Zhenhao Hong <zhenhaohong@gmail.com>
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ hw/virtio.c | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/hw/virtio.c b/hw/virtio.c
+index c26feff..42897bf 100644
+--- a/hw/virtio.c
++++ b/hw/virtio.c
+@@ -421,6 +421,11 @@ int virtqueue_pop(VirtQueue *vq, VirtQueueElement *elem)
+ /* When we start there are none of either input nor output. */
+ elem->out_num = elem->in_num = 0;
+
++ if (vq->inuse >= vq->vring.num) {
++ fprintf(stderr, "Virtqueue size exceeded");
++ exit(1);
++ }
++
+ i = head = virtqueue_get_head(vq, vq->last_avail_idx++);
+ do {
+ struct iovec *sg;
+--
+2.1.4
+