CVE-2019-7221

Impact:
Important
Public Date:
2019-02-07
CWE:
CWE-416
Bugzilla:
1671904: CVE-2019-7221 Kernel: KVM: nVMX: use-after-free of the hrtimer for emulation of the preemption timer
A use-after-free vulnerability was found in the way the Linux kernel's KVM hypervisor emulates a preemption timer for L2 guests when nested (=1) virtualization is enabled. This high resolution timer(hrtimer) runs when a L2 guest is active. After VM exit, the sync_vmcs12() timer object is stopped. The use-after-free occurs if the timer object is freed before calling sync_vmcs12() routine. A guest user/process could use this flaw to crash the host kernel resulting in a denial of service or, potentially, gain privileged access to a system.

Find out more about CVE-2019-7221 from the MITRE CVE dictionary dictionary and NIST NVD.

Statement

This issue does not affect the version of the kernel package as shipped with Red Hat Enterprise Linux 5, 6 and Red Hat Enterprise MRG 2.

This issue affects the versions of Linux kernel as shipped with Red Hat Enterprise Linux 7. Future kernel updates for Red Hat Enterprise Linux 7 may address this issue.

Note: Impact on Red Hat Enterprise Linux 7 kernel is limited, as it requires that nested virtualization feature is enabled on a system. Nested Virtualization feature is available only as - Technology Preview.

CVSS v3 metrics

CVSS3 Base Score 7.5
CVSS3 Base Metrics CVSS:3.0/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
Attack Vector Local
Attack Complexity High
Privileges Required High
User Interaction None
Scope Changed
Confidentiality High
Integrity Impact High
Availability Impact High

Red Hat Security Errata

Platform Errata Release Date
Red Hat Enterprise Linux 7 (kernel) RHSA-2019:0818 2019-04-23
Red Hat Enterprise Linux for Real Time for NFV (v. 7) (kernel-rt) RHSA-2019:0833 2019-04-23

Affected Packages State

Platform Package State
Red Hat Enterprise MRG 2 kernel-rt Not affected
Red Hat Enterprise Linux 8 kernel Not affected
Red Hat Enterprise Linux 8 kernel-rt Not affected
Red Hat Enterprise Linux 7 kernel-alt Not affected
Red Hat Enterprise Linux 6 kernel Not affected
Red Hat Enterprise Linux 5 kernel Not affected

Acknowledgements

Red Hat would like to thank Felix Wilhelm (Google) for reporting this issue.
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