CVE-2023-46842

Name	CVE-2023-46842
Description	Unlike 32-bit PV guests, HVM guests may switch freely between 64-bit and other modes. This in particular means that they may set registers used to pass 32-bit-mode hypercall arguments to values outside of the range 32-bit code would be able to set them to. When processing of hypercalls takes a considerable amount of time, the hypervisor may choose to invoke a hypercall continuation. Doing so involves putting (perhaps updated) hypercall arguments in respective registers. For guests not running in 64-bit mode this further involves a certain amount of translation of the values. Unfortunately internal sanity checking of these translated values assumes high halves of registers to always be clear when invoking a hypercall. When this is found not to be the case, it triggers a consistency check in the hypervisor and causes a crash.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
References	DSA-5836-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
xen (PTS)	bullseye	4.14.6-1	vulnerable
	bullseye (security)	4.14.5+94-ge49571868d-1	vulnerable
	bookworm	4.17.3+10-g091466ba55-1~deb12u1	vulnerable
	bookworm (security)	4.17.5+23-ga4e5191dc0-1	fixed
	trixie	4.17.3+36-g54dacb5c02-1	vulnerable
	sid	4.19.1-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin
xen	source	experimental	4.19.0+14-g0918434e0f-1~exp1
xen	source	buster	(not affected)
xen	source	bullseye	(unfixed)	end-of-life
xen	source	bookworm	4.17.5+23-ga4e5191dc0-1		DSA-5836-1
xen	source	(unstable)	4.19.1-1

Notes

[bullseye] - xen <end-of-life> (EOLed in Bullseye)
[buster] - xen <not-affected> (Vulnerable code not present)
https://xenbits.xen.org/xsa/advisory-454.html