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| author | Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> | 2011-05-08 22:29:07 +0100 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2011-06-12 10:33:38 +0300 |
| commit | 7157e2e23e89adcd436caeab31fdd6b47eded377 (patch) | |
| tree | 5012c5e003f5d66032ef7892240ad8c9a9abe5eb /hw/virtio-pci.c | |
| parent | e75ccf2c033fb0503d6cb7ddd0fd1dfa0aa4fc16 (diff) | |
| download | focaccia-qemu-7157e2e23e89adcd436caeab31fdd6b47eded377.tar.gz focaccia-qemu-7157e2e23e89adcd436caeab31fdd6b47eded377.zip | |
virtio: guard against negative vq notifies
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 <stefanha@linux.vnet.ibm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'hw/virtio-pci.c')
| -rw-r--r-- | hw/virtio-pci.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c index 270e2c7438..b86c441623 100644 --- a/hw/virtio-pci.c +++ b/hw/virtio-pci.c @@ -348,7 +348,9 @@ 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)) { |