CVE request virglrenderer: null pointer dereference in vrend_clear

[P J P <ppandit () redhat com>]

  Hello,

Virgil 3d project, used by Quick Emulator(Qemu) to implement 3D GPU support 
for the virtio GPU, is vulnerable to a null pointer dereference issue. It 
could occur when a guest invokes a virgl 'VIRGL_CCMD_CLEAR' command.

A guest user/process could use this flaw to crash Qemu process resulting in 
DoS.

Upstream patch:
---------------
  -> https://cgit.freedesktop.org/virglrenderer/commit/?id=48f67f60967f963b698ec8df57ec6912a43d6282

Reference:
----------
  -> https://bugzilla.redhat.com/show_bug.cgi?id=1420246

This issue was reported by Mr Li Qiang of 360.cn Inc.

Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
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