Oracle Linux: CVE-2017-7261: ELSA-2020-5671: Unbreakable Enterprise kernel security update (IMPORTANT) (Multiple Advisories)

The vmw_surface_define_ioctl function in drivers/gpu/drm/vmwgfx/vmwgfx_surface.c in the Linux kernel through 4.10.5 does not check for a zero value of certain levels data, which allows local users to cause a denial of service (ZERO_SIZE_PTR dereference, and GPF and possibly panic) via a crafted ioctl call for a /dev/dri/renderD* device.
It was found that in the Linux kernel, in vmw_surface_define_ioctl() function in 'drivers/gpu/drm/vmwgfx/vmwgfx_surface.c' file, a 'num_sizes' parameter is assigned a user-controlled value which is not checked if it is zero. This is used in a call to kmalloc() and later leads to dereferencing ZERO_SIZE_PTR, which in turn leads to a GPF and possibly to a kernel panic.