From ce317461573bac12b10d67699b4ddf1f97cf066c Mon Sep 17 00:00:00 2001
From: Jason Wang <jasowang@redhat.com>
Date: Fri, 25 Sep 2015 13:21:28 +0800
Subject: [PATCH] virtio: introduce virtqueue_unmap_sg()

Factor out sg unmapping logic. This will be reused by the patch that
can discard descriptor.

Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Andrew James <andrew.james@hpe.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Upstream-Status: Backport

git.qemu.org/?p=qemu.git;a=commit;h=ce317461573bac12b10d67699b4ddf1f97cf066c

CVE: CVE-2015-7295 patch #1
[Yocto # 9013]

Signed-off-by: Armin Kuster <akuster@mvista.com>

---
 hw/virtio/virtio.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

Index: qemu-2.4.0/hw/virtio/virtio.c
===================================================================
--- qemu-2.4.0.orig/hw/virtio/virtio.c
+++ qemu-2.4.0/hw/virtio/virtio.c
@@ -243,14 +243,12 @@ int virtio_queue_empty(VirtQueue *vq)
     return vring_avail_idx(vq) == vq->last_avail_idx;
 }
 
-void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,
-                    unsigned int len, unsigned int idx)
+static void virtqueue_unmap_sg(VirtQueue *vq, const VirtQueueElement *elem,
+                               unsigned int len)
 {
     unsigned int offset;
     int i;
 
-    trace_virtqueue_fill(vq, elem, len, idx);
-
     offset = 0;
     for (i = 0; i < elem->in_num; i++) {
         size_t size = MIN(len - offset, elem->in_sg[i].iov_len);
@@ -266,6 +264,14 @@ void virtqueue_fill(VirtQueue *vq, const
         cpu_physical_memory_unmap(elem->out_sg[i].iov_base,
                                   elem->out_sg[i].iov_len,
                                   0, elem->out_sg[i].iov_len);
+}
+
+void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,
+                    unsigned int len, unsigned int idx)
+{
+    trace_virtqueue_fill(vq, elem, len, idx);
+
+    virtqueue_unmap_sg(vq, elem, len);
 
     idx = (idx + vring_used_idx(vq)) % vq->vring.num;