diff mbox series

[v3,QEMU,1/3] virtio-balloon: Prevent guest from starting a report when we didn't request one

Message ID 20200720175115.21935.99563.stgit@localhost.localdomain (mailing list archive)
State New, archived
Headers show
Series virtio-balloon: Free page hinting clean-ups | expand

Commit Message

Alexander Duyck July 20, 2020, 5:51 p.m. UTC 
From: Alexander Duyck <alexander.h.duyck@linux.intel.com>

Based on code review it appears possible for the driver to force the device
out of a stopped state when hinting by repeating the last ID it was
provided.

Prevent this by only allowing a transition to the start state when we are
in the requested state. This way the driver is only allowed to send one
descriptor that will transition the device into the start state. All others
will leave it in the stop state once it has finished.

Fixes: c13c4153f76d ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
---
 hw/virtio/virtio-balloon.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index e670f1e59534..ce70adcc6925 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -526,7 +526,8 @@  static bool get_free_page_hints(VirtIOBalloon *dev)
             ret = false;
             goto out;
         }
-        if (id == dev->free_page_report_cmd_id) {
+        if (dev->free_page_report_status == FREE_PAGE_REPORT_S_REQUESTED &&
+            id == dev->free_page_report_cmd_id) {
             dev->free_page_report_status = FREE_PAGE_REPORT_S_START;
         } else {
             /*