An issue was discovered in Xen through 4.11.x allowing x86 PV guest OS users to cause a denial of service or gain privileges by leveraging incorrect use of the HVM physmap concept for PV domains.
The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Xen | Xen | * | 4.11.2 (including) |
| Xen | Ubuntu | bionic | * |
| Xen | Ubuntu | disco | * |
| Xen | Ubuntu | eoan | * |
| Xen | Ubuntu | esm-infra/bionic | * |
| Xen | Ubuntu | esm-infra/xenial | * |
| Xen | Ubuntu | groovy | * |
| Xen | Ubuntu | hirsute | * |
| Xen | Ubuntu | impish | * |
| Xen | Ubuntu | trusty | * |
| Xen | Ubuntu | xenial | * |
Locking is a type of synchronization behavior that ensures that multiple independently-operating processes or threads do not interfere with each other when accessing the same resource. All processes/threads are expected to follow the same steps for locking. If these steps are not followed precisely - or if no locking is done at all - then another process/thread could modify the shared resource in a way that is not visible or predictable to the original process. This can lead to data or memory corruption, denial of service, etc.