An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a denial of service because of a bad error path in GNTTABOP_map_grant. Grant table operations are expected to return 0 for success, and a negative number for errors. Some misplaced brackets cause one error path to return 1 instead of a negative value. The grant table code in Linux treats this condition as success, and proceeds with incorrectly initialised state. A buggy or malicious guest can construct its grant table in such a way that, when a backend domain tries to map a grant, it hits the incorrect error path. This will crash a Linux based dom0 or backend domain.
Source: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-11743
Reference (s):
- http://xenbits.xen.org/xsa/advisory-316.html
- DEBIAN:DSA-4723
- URL: https://www.debian.org/security/2020/dsa-4723
- FEDORA:FEDORA-2020-295ed0b1e0
- URL: https://lists.fedoraproject.org/archives/list/[email protected]/message/5M2XRNCHOGGTJQBZQJ7DCV6ZNAKN3LE2/