CVE-2021-26930

Published: 17 February 2021

An issue was discovered in the Linux kernel 3.11 through 5.10.16, as used by Xen. To service requests to the PV backend, the driver maps grant references provided by the frontend. In this process, errors may be encountered. In one case, an error encountered earlier might be discarded by later processing, resulting in the caller assuming successful mapping, and hence subsequent operations trying to access space that wasn't mapped. In another case, internal state would be insufficiently updated, preventing safe recovery from the error. This affects drivers/block/xen-blkback/blkback.c.

From the Ubuntu Security Team

Olivier Benjamin, Norbert Manthey, Martin Mazein, and Jan H. Schönherr discovered that the Xen paravirtualization backend in the Linux kernel did not properly propagate errors to frontend drivers in some situations. An attacker in a guest VM could possibly use this to cause a denial of service (host domain crash).

Status

Severity score breakdown

References

• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-26930
• http://xenbits.xen.org/xsa/advisory-365.html
• https://www.openwall.com/lists/oss-security/2021/02/16/6
• https://ubuntu.com/security/notices/USN-4904-1
• https://ubuntu.com/security/notices/USN-4909-1
• https://ubuntu.com/security/notices/USN-4946-1
• https://ubuntu.com/security/notices/USN-4949-1
• NVD
• Launchpad
• Debian