SB2021100530 - Fedora 35 update for xen
Published: October 5, 2021
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 security vulnerability.
1) Use-after-free (CVE-ID: CVE-2021-28702)
The vulnerability allows a remote user to perform a escalate privileges on the system.
The vulnerability exists due to a design error in PCI devices with RMRRs. If such device is connected through to a guest OS, then on guest OS shutdown of 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.
Administrators of guests which have been assigned RMRR-using PCI devices can cause denial of service and other problems, possibly including escalation of privilege.
Remediation
Install update from vendor's website.