hw/virtio-iommu: Fix potential OOB access in virtio_iommu_handle_command()

In the virtio_iommu_handle_command() when a PROBE request is handled,
output_size takes a value greater than the tail size and on a subsequent
iteration we can get a stack out-of-band access. Initialize the
output_size on each iteration.

The issue was found with ASAN. Credits to:
Yiming Tao(Zhejiang University)
Gaoning Pan(Zhejiang University)

Fixes: 1733eebb9e ("virtio-iommu: Implement RESV_MEM probe request")
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reported-by: Mauro Matteo Cascella <mcascell@redhat.com>
Cc: qemu-stable@nongnu.org

Message-Id: <20230717162126.11693-1-eric.auger@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit cf2f89edf3)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
This commit is contained in:
Eric Auger 2023-07-17 18:21:26 +02:00 committed by Michael Tokarev
parent 5bbd092495
commit c315f73841

View File

@ -727,13 +727,15 @@ static void virtio_iommu_handle_command(VirtIODevice *vdev, VirtQueue *vq)
VirtIOIOMMU *s = VIRTIO_IOMMU(vdev);
struct virtio_iommu_req_head head;
struct virtio_iommu_req_tail tail = {};
size_t output_size = sizeof(tail), sz;
VirtQueueElement *elem;
unsigned int iov_cnt;
struct iovec *iov;
void *buf = NULL;
size_t sz;
for (;;) {
size_t output_size = sizeof(tail);
elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
if (!elem) {
return;