CVE-2021-28702

Name	CVE-2021-28702
Description	PCI devices with RMRRs not deassigned correctly Certain PCI devices in a system might be assigned Reserved Memory Regions (specified via Reserved Memory Region Reporting, "RMRR"). These are typically used for platform tasks such as legacy USB emulation. If such a device is passed through to a guest, then on guest shutdown the device is not properly deassigned. The IOMMU configuration for these devices which are not properly deassigned ends up pointing to a freed data structure, including the IO Pagetables. Subsequent DMA or interrupts from the device will have unpredictable behaviour, ranging from IOMMU faults to memory corruption.
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-5017-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
xen (PTS)	bullseye	4.14.6-1	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	Origin
xen	source	stretch	(not affected)
xen	source	buster	(not affected)
xen	source	bullseye	4.14.3+32-g9de3671772-1~deb11u1	DSA-5017-1
xen	source	(unstable)	4.14.3+32-g9de3671772-1

Notes

[buster] - xen <not-affected> (Vulnerable code introduced later)
[stretch] - xen <not-affected> (Vulnerable code introduced later)
https://xenbits.xen.org/xsa/advisory-386.html