Описание
Security update for xen
This update for xen fixes the following issues:
- CVE-2020-15563: Fixed inverted code paths in x86 dirty VRAM tracking (bsc#1173377).
- CVE-2020-15565: Fixed insufficient cache write-back under VT-d (bsc#1173378).
- CVE-2020-15567: Fixed non-atomic modification of live EPT PTE (bsc#1173380).
Список пакетов
HPE Helion OpenStack 8
SUSE Enterprise Storage 5
SUSE Linux Enterprise Server 12 SP3-BCL
SUSE Linux Enterprise Server 12 SP3-LTSS
SUSE Linux Enterprise Server for SAP Applications 12 SP3
SUSE OpenStack Cloud 8
SUSE OpenStack Cloud Crowbar 8
Ссылки
- Link for SUSE-SU-2020:1886-1
- E-Mail link for SUSE-SU-2020:1886-1
- SUSE Security Ratings
- SUSE Bug 1173377
- SUSE Bug 1173378
- SUSE Bug 1173380
- SUSE CVE CVE-2020-15563 page
- SUSE CVE CVE-2020-15565 page
- SUSE CVE CVE-2020-15567 page
Описание
An issue was discovered in Xen through 4.13.x, allowing x86 HVM guest OS users to cause a hypervisor crash. An inverted conditional in x86 HVM guests' dirty video RAM tracking code allows such guests to make Xen de-reference a pointer guaranteed to point at unmapped space. A malicious or buggy HVM guest may cause the hypervisor to crash, resulting in Denial of Service (DoS) affecting the entire host. Xen versions from 4.8 onwards are affected. Xen versions 4.7 and earlier are not affected. Only x86 systems are affected. Arm systems are not affected. Only x86 HVM guests using shadow paging can leverage the vulnerability. In addition, there needs to be an entity actively monitoring a guest's video frame buffer (typically for display purposes) in order for such a guest to be able to leverage the vulnerability. x86 PV guests, as well as x86 HVM guests using hardware assisted paging (HAP), cannot leverage the vulnerability.
Затронутые продукты
Ссылки
- CVE-2020-15563
- SUSE Bug 1173377
Описание
An issue was discovered in Xen through 4.13.x, allowing x86 Intel HVM guest OS users to cause a host OS denial of service or possibly gain privileges because of insufficient cache write-back under VT-d. When page tables are shared between IOMMU and CPU, changes to them require flushing of both TLBs. Furthermore, IOMMUs may be non-coherent, and hence prior to flushing IOMMU TLBs, a CPU cache also needs writing back to memory after changes were made. Such writing back of cached data was missing in particular when splitting large page mappings into smaller granularity ones. A malicious guest may be able to retain read/write DMA access to frames returned to Xen's free pool, and later reused for another purpose. Host crashes (leading to a Denial of Service) and privilege escalation cannot be ruled out. Xen versions from at least 3.2 onwards are affected. Only x86 Intel systems are affected. x86 AMD as well as Arm systems are not affected. Only x86 HVM guests using hardware assisted paging (HAP), having a passed through PCI device assigned, and having page table sharing enabled can leverage the vulnerability. Note that page table sharing will be enabled (by default) only if Xen considers IOMMU and CPU large page size support compatible.
Затронутые продукты
Ссылки
- CVE-2020-15565
- SUSE Bug 1173378
Описание
An issue was discovered in Xen through 4.13.x, allowing Intel guest OS users to gain privileges or cause a denial of service because of non-atomic modification of a live EPT PTE. When mapping guest EPT (nested paging) tables, Xen would in some circumstances use a series of non-atomic bitfield writes. Depending on the compiler version and optimisation flags, Xen might expose a dangerous partially written PTE to the hardware, which an attacker might be able to race to exploit. A guest administrator or perhaps even an unprivileged guest user might be able to cause denial of service, data corruption, or privilege escalation. Only systems using Intel CPUs are vulnerable. Systems using AMD CPUs, and Arm systems, are not vulnerable. Only systems using nested paging (hap, aka nested paging, aka in this case Intel EPT) are vulnerable. Only HVM and PVH guests can exploit the vulnerability. The presence and scope of the vulnerability depends on the precise optimisations performed by the compiler used to build Xen. If the compiler generates (a) a single 64-bit write, or (b) a series of read-modify-write operations in the same order as the source code, the hypervisor is not vulnerable. For example, in one test build using GCC 8.3 with normal settings, the compiler generated multiple (unlocked) read-modify-write operations in source-code order, which did not constitute a vulnerability. We have not been able to survey compilers; consequently we cannot say which compiler(s) might produce vulnerable code (with which code-generation options). The source code clearly violates the C rules, and thus should be considered vulnerable.
Затронутые продукты
Ссылки
- CVE-2020-15567
- SUSE Bug 1173380
- SUSE Bug 1178658