Description
When passing through PCI devices, the detach logic in libxl won't remove access permissions to any 64bit memory BARs the device might have. As a result a domain can still have access any 64bit memory BAR when such device is no longer assigned to the domain. For PV domains the permission leak allows the domain itself to map the memory in the page-tables. For HVM it would require a compromised device model or stubdomain to map the leaked memory into the HVM domain p2m.
Product status
consult Xen advisory XSA-476
Credits
This issue was discovered by Jiqian Chen of AMD and diagnosed as a
security issue by Roger Pau Monné of XenServer.
References
xenbits.xen.org/xsa/advisory-476.html
www.openwall.com/lists/oss-security/2025/10/24/1
xenbits.xenproject.org/xsa/advisory-476.html
