Missing Authorization Affecting kernel-rt package, versions <0:4.18.0-305.25.1.rt7.97.el8_4
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Test your applications- Snyk ID SNYK-CENTOS8-KERNELRT-2126440
- published 17 Aug 2021
- disclosed 16 Aug 2021
Introduced: 16 Aug 2021
CVE-2021-3656 Open this link in a new tabHow to fix?
Upgrade Centos:8 kernel-rt to version 0:4.18.0-305.25.1.rt7.97.el8_4 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-rt package and not the kernel-rt package as distributed by Centos.
See How to fix? for Centos:8 relevant fixed versions and status.
A flaw was found in the KVM's AMD code for supporting SVM nested virtualization. The flaw occurs when processing the VMCB (virtual machine control block) provided by the L1 guest to spawn/handle a nested guest (L2). Due to improper validation of the "virt_ext" field, this issue could allow a malicious L1 to disable both VMLOAD/VMSAVE intercepts and VLS (Virtual VMLOAD/VMSAVE) for the L2 guest. As a result, the L2 guest would be allowed to read/write physical pages of the host, resulting in a crash of the entire system, leak of sensitive data or potential guest-to-host escape.
References
- https://access.redhat.com/security/cve/CVE-2021-3656
- https://access.redhat.com/errata/RHSA-2021:4088
- https://bugzilla.redhat.com/show_bug.cgi?id=1983988
- https://git.kernel.org/pub/scm/virt/kvm/kvm.git/commit/?id=c7dfa4009965a9b2d7b329ee970eb8da0d32f0bc
- https://github.com/torvalds/linux/commit/c7dfa4009965a9b2d7b329ee970eb8da0d32f0bc
- https://www.openwall.com/lists/oss-security/2021/08/16/1