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Gentoo Linux: CVE-2020-25603: Xen: Multiple vulnerabilities

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Gentoo Linux: CVE-2020-25603: Xen: Multiple vulnerabilities

Severity
5
CVSS
(AV:L/AC:L/Au:N/C:P/I:P/A:P)
Published
09/23/2020
Created
11/13/2020
Added
11/12/2020
Modified
11/12/2020

Description

An issue was discovered in Xen through 4.14.x. There are missing memory barriers when accessing/allocating an event channel. Event channels control structures can be accessed lockless as long as the port is considered to be valid. Such a sequence is missing an appropriate memory barrier (e.g., smp_*mb()) to prevent both the compiler and CPU from re-ordering access. A malicious guest may be able to cause a hypervisor crash resulting in a Denial of Service (DoS). Information leak and privilege escalation cannot be excluded. Systems running all versions of Xen are affected. Whether a system is vulnerable will depend on the CPU and compiler used to build Xen. For all systems, the presence and the scope of the vulnerability depend on the precise re-ordering performed by the compiler used to build Xen. We have not been able to survey compilers; consequently we cannot say which compiler(s) might produce vulnerable code (with which code generation options). GCC documentation clearly suggests that re-ordering is possible. Arm systems will also be vulnerable if the CPU is able to re-order memory access. Please consult your CPU vendor. x86 systems are only vulnerable if a compiler performs re-ordering.

Solution(s)

  • gentoo-linux-upgrade-app-emulation-xen
  • gentoo-linux-upgrade-app-emulation-xen-tools

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