In the Linux kernel 4.14 longterm through 4.14.165 and 4.19 longterm through 4.19.96 (and 5.x before 5.2), there is a use-after-free (write) in the i915_ppgtt_close function in drivers/gpu/drm/i915/i915_gem_gtt.c, aka CID-7dc40713618c. This is related to i915_gem_context_destroy_ioctl in drivers/gpu/drm/i915/i915_gem_context.c.
https://usn.ubuntu.com/4287-2/
https://usn.ubuntu.com/4287-1/
https://usn.ubuntu.com/4285-1/
https://usn.ubuntu.com/4255-2/
https://usn.ubuntu.com/4255-1/
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.2
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1859522
http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00021.html