[PATCH v1 5/6] s390/vfio_ccw: ensure index for read/write regions are within range

[Eric Farman <farman@linux.ibm.com>]

The introduction of the capability chain rightly clamped the
region indexes to the range of the capabilities itself, but
neglected to do so for the existing read/write regions which
should also be enforced.

Fixes: db8e5d17ac03 ("vfio-ccw: add capabilities chain")
Cc: stable@vger.kernel.org
Cc: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
 drivers/s390/cio/vfio_ccw_ops.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index afe9448c165e..63cf5850bd50 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -245,6 +245,8 @@ static ssize_t vfio_ccw_mdev_read(struct vfio_device *vdev,
 	if (index >= VFIO_CCW_NUM_REGIONS + private->num_regions)
 		return -EINVAL;
 
+	index = array_index_nospec(index, VFIO_CCW_NUM_REGIONS + private->num_regions);
+
 	switch (index) {
 	case VFIO_CCW_CONFIG_REGION_INDEX:
 		return vfio_ccw_mdev_read_io_region(private, buf, count, ppos);
@@ -297,6 +299,8 @@ static ssize_t vfio_ccw_mdev_write(struct vfio_device *vdev,
 	if (index >= VFIO_CCW_NUM_REGIONS + private->num_regions)
 		return -EINVAL;
 
+	index = array_index_nospec(index, VFIO_CCW_NUM_REGIONS + private->num_regions);
+
 	switch (index) {
 	case VFIO_CCW_CONFIG_REGION_INDEX:
 		return vfio_ccw_mdev_write_io_region(private, buf, count, ppos);
-- 
2.53.0