From f2e49bb91854240284a7cf86469f7e03fd936fc5 Mon Sep 17 00:00:00 2001 From: Xiao Wang Date: Thu, 2 Jun 2011 05:12:07 -0300 Subject: [RHEL6 qemu-kvm PATCH 01/23] virtio: guard against negative vq notifies RH-Author: Xiao Wang Message-id: <20110602051207.28777.15475.stgit@dhcp-91-7.nay.redhat.com.englab.nay.redhat.com> Patchwork-id: 26205 O-Subject: [RHEL6.2/RHEL6.1Z qemu-kvm PATCH] virtio: guard against negative vq notifies Bugzilla: 707094 RH-Acked-by: Michael S. Tsirkin RH-Acked-by: Markus Armbruster RH-Acked-by: Amit Shah RH-Acked-by: Amos Kong From: Stefan Hajnoczi Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=707094 Upstream: in Michael's tree Brew: https://brewweb.devel.redhat.com/taskinfo?taskID=3365023 Test status: Just make sure virtio works as normal in my local desktop. The virtio_queue_notify() function checks that the virtqueue number is less than the maximum number of virtqueues. A signed comparison is used but the virtqueue number could be negative if a buggy or malicious guest is run. This results in memory accesses outside of the virtqueue array. It is risky doing input validation in common code instead of at the guest<->host boundary. Note that virtio_queue_set_addr(), virtio_queue_get_addr(), virtio_queue_get_num(), and many other virtio functions do *not* validate the virtqueue number argument. Instead of fixing the comparison in virtio_queue_notify(), move the comparison to the virtio bindings (just like VIRTIO_PCI_QUEUE_SEL) where we have a uint32_t value and can avoid ever calling into common virtio code if the virtqueue number is invalid. Signed-off-by: Stefan Hajnoczi Signed-off-by: Michael S. Tsirkin (cherry picked from commit 3eb9904855739be82c439c8a5067d71877f85473) --- 0 files changed, 0 insertions(+), 0 deletions(-) Signed-off-by: Eduardo Habkost --- hw/syborg_virtio.c | 4 +++- hw/virtio-pci.c | 4 +++- hw/virtio.c | 4 +--- 3 files changed, 7 insertions(+), 5 deletions(-) diff --git a/hw/syborg_virtio.c b/hw/syborg_virtio.c index dd0a87b..9acb715 100644 --- a/hw/syborg_virtio.c +++ b/hw/syborg_virtio.c @@ -147,7 +147,9 @@ static void syborg_virtio_writel(void *opaque, target_phys_addr_t offset, vdev->queue_sel = value; break; case SYBORG_VIRTIO_QUEUE_NOTIFY: - virtio_queue_notify(vdev, value); + if (value < VIRTIO_PCI_QUEUE_MAX) { + virtio_queue_notify(vdev, value); + } break; case SYBORG_VIRTIO_STATUS: virtio_set_status(vdev, value); diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c index f9eb9ec..3098d34 100644 --- a/hw/virtio-pci.c +++ b/hw/virtio-pci.c @@ -345,7 +345,9 @@ static void virtio_ioport_write(void *opaque, uint32_t addr, uint32_t val) vdev->queue_sel = val; break; case VIRTIO_PCI_QUEUE_NOTIFY: - virtio_queue_notify(vdev, val); + if (val < VIRTIO_PCI_QUEUE_MAX) { + virtio_queue_notify(vdev, val); + } break; case VIRTIO_PCI_STATUS: if (!(val & VIRTIO_CONFIG_S_DRIVER_OK)) { diff --git a/hw/virtio.c b/hw/virtio.c index 0b6344e..786b6fe 100644 --- a/hw/virtio.c +++ b/hw/virtio.c @@ -585,9 +585,7 @@ void virtio_queue_notify_vq(VirtQueue *vq) void virtio_queue_notify(VirtIODevice *vdev, int n) { - if (n < VIRTIO_PCI_QUEUE_MAX) { - virtio_queue_notify_vq(&vdev->vq[n]); - } + virtio_queue_notify_vq(&vdev->vq[n]); } uint16_t virtio_queue_vector(VirtIODevice *vdev, int n) -- 1.7.3.2