CVE-2020-35517 QEMU: virtiofsd: potential privileged host device access from guest

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

  Hello,

A potential host privilege escalation issue was found in the virtio-fs shared 
file system daemon (virtiofsd) of the QEMU. Virtio-fs daemon shares host 
directory tree with a guest VM. The said privilege escalation scenario may 
occur if a privileged guest user was to create device special file in the 
shared directory and use it to r/w access host devices. A privileged guest 
user may use this flaw to arbitrarily access (r/w) host files resulting in DoS 
scenario or may potentially escalate privileges on the host.

Upstream patch:
---------------
  -> https://lists.gnu.org/archive/html/qemu-devel/2021-01/msg05461.html

* This issue was reported by Alex Xu (CC'd).

* 'CVE-2020-35517' assigned by Red Hat Inc.

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