CVE-2021-3308

Name	CVE-2021-3308
Description	An issue was discovered in Xen 4.12.3 through 4.12.4 and 4.13.1 through 4.14.x. An x86 HVM guest with PCI pass through devices can force the allocation of all IDT vectors on the system by rebooting itself with MSI or MSI-X capabilities enabled and entries setup. Such reboots will leak any vectors used by the MSI(-X) entries that the guest might had enabled, and hence will lead to vector exhaustion on the system, not allowing further PCI pass through devices to work properly. HVM guests with PCI pass through devices can mount a Denial of Service (DoS) attack affecting the pass through of PCI devices to other guests or the hardware domain. In the latter case, this would affect the entire host.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	981052

Vulnerable and fixed packages

The table below lists information on source packages.

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

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

Package	Type	Release	Fixed Version	Debian Bugs
xen	source	stretch	(not affected)
xen	source	buster	(not affected)
xen	source	(unstable)	4.14.1+11-gb0b734a8b3-1	981052

Notes

[buster] - xen <not-affected> (Vulnerable code introduced later)
[stretch] - xen <not-affected> (Vulnerable code introduced later)
https://xenbits.xen.org/xsa/advisory-360.html
Introduced by: https://xenbits.xen.org/gitweb/?p=xen.git;a=commit;h=5b58dad089880127674d460494d1a9d68109b3d7 (4.14.0-rc1)
Issue backported to 4.12.3 and 4.13.1
Fixed by: https://xenbits.xen.org/gitweb/?p=xen.git;a=commit;h=58427889f5a420cc5226f88524b3228f90b72a58