Linux kernel: drm/vmwgfx: 4 byte read of uninitialised kernel memory in vmw_gb_surface_define_ioctl()

[Murray McAllister <murray.mcallister () insomniasec com>]

The vmw_gb_surface_define_ioctl() function (accessible via
DRM_IOCTL_VMW_GB_SURFACE_CREATE) defines a backup_handle variable but
does not give it an initial value. If you attempt to create a GB
surface, and provide 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.

Upstream commit:

https://github.com/torvalds/linux/commit/07678eca2cf9c9a18584e546c2b2a0d0c9a3150c

CVE:

I'll request one now and reply once I have one.

Chur