CVE-2017-9605

The vmw_gb_surface_define_ioctl function (accessible via
DRM_IOCTL_VMW_GB_SURFACE_CREATE) in drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
in the Linux kernel through 4.11.4 defines a backup_handle variable but
does not give it an initial value. If one attempts to create a GB surface,
with a previously allocated DMA buffer to be used as a backup buffer, the
backup_handle variable does not get written to and is then later returned
to user space, allowing local users to obtain sensitive information from
uninitialized kernel memory via a crafted ioctl call.