SUSE SLES15 Security Update : xen (SUSE-SU-2021:3842-1)

high Nessus Plugin ID 155804

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Synopsis

The remote SUSE host is missing one or more security updates.

Description

The remote SUSE Linux SLES15 / SLES_SAP15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2021:3842-1 advisory.

- Another race in XENMAPSPACE_grant_table handling Guests are permitted access to certain Xen-owned pages of memory. The majority of such pages remain allocated / associated with a guest for its entire lifetime.
Grant table v2 status pages, however, are de-allocated when a guest switches (back) from v2 to v1. Freeing such pages requires that the hypervisor enforce that no parallel request can result in the addition of a mapping of such a page to a guest. That enforcement was missing, allowing guests to retain access to pages that were freed and perhaps re-used for other purposes. Unfortunately, when XSA-379 was being prepared, this similar issue was not noticed. (CVE-2021-28701)

- PoD operations on misaligned GFNs T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] x86 HVM and PVH guests may be started in populate- on-demand (PoD) mode, to provide a way for them to later easily have more memory assigned. Guests are permitted to control certain P2M aspects of individual pages via hypercalls. These hypercalls may act on ranges of pages specified via page orders (resulting in a power-of-2 number of pages). The implementation of some of these hypercalls for PoD does not enforce the base page frame number to be suitably aligned for the specified order, yet some code involved in PoD handling actually makes such an assumption. These operations are XENMEM_decrease_reservation (CVE-2021-28704) and XENMEM_populate_physmap (CVE-2021-28707), the latter usable only by domains controlling the guest, i.e. a de-privileged qemu or a stub domain.
(Patch 1, combining the fix to both these two issues.) In addition handling of XENMEM_decrease_reservation can also trigger a host crash when the specified page order is neither 4k nor 2M nor 1G (CVE-2021-28708, patch 2). (CVE-2021-28704, CVE-2021-28707, CVE-2021-28708)

- issues with partially successful P2M updates on x86 T[his CNA information record relates to multiple CVEs;
the text explains which aspects/vulnerabilities correspond to which CVE.] x86 HVM and PVH guests may be started in populate-on-demand (PoD) mode, to provide a way for them to later easily have more memory assigned. Guests are permitted to control certain P2M aspects of individual pages via hypercalls. These hypercalls may act on ranges of pages specified via page orders (resulting in a power-of-2 number of pages). In some cases the hypervisor carries out the requests by splitting them into smaller chunks. Error handling in certain PoD cases has been insufficient in that in particular partial success of some operations was not properly accounted for. There are two code paths affected - page removal (CVE-2021-28705) and insertion of new pages (CVE-2021-28709). (We provide one patch which combines the fix to both issues.) (CVE-2021-28705, CVE-2021-28709)

- guests may exceed their designated memory limit When a guest is permitted to have close to 16TiB of memory, it may be able to issue hypercalls to increase its memory allocation beyond the administrator established limit. This is a result of a calculation done with 32-bit precision, which may overflow. It would then only be the overflowed (and hence small) number which gets compared against the established upper bound. (CVE-2021-28706)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Update the affected packages.

Plugin Details

Severity: High

ID: 155804

File Name: suse_SU-2021-3842-1.nasl

Version: 1.7

Type: local

Agent: unix

Family: SuSE Local Security Checks

Published: 12/2/2021

Updated: 7/13/2023

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Nessus

Risk Information

VPR

Risk Factor: High

Score: 7.3

CVSS v2

Risk Factor: Medium

Base Score: 6.9

Temporal Score: 5.1

Vector: CVSS2#AV:L/AC:M/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2021-28709

CVSS v3

Risk Factor: High

Base Score: 8.8

Temporal Score: 7.7

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

CVSS Score Source: CVE-2021-28708

Vulnerability Information

CPE: p-cpe:/a:novell:suse_linux:xen, p-cpe:/a:novell:suse_linux:xen-devel, p-cpe:/a:novell:suse_linux:xen-libs, p-cpe:/a:novell:suse_linux:xen-tools, p-cpe:/a:novell:suse_linux:xen-tools-domu, cpe:/o:novell:suse_linux:15

Required KB Items: Host/local_checks_enabled, Host/cpu, Host/SuSE/release, Host/SuSE/rpm-list

Exploit Ease: No known exploits are available

Patch Publication Date: 12/1/2021

Vulnerability Publication Date: 9/8/2021

Reference Information

CVE: CVE-2021-28701, CVE-2021-28704, CVE-2021-28705, CVE-2021-28706, CVE-2021-28707, CVE-2021-28708, CVE-2021-28709

IAVB: 2021-B-0068-S

SuSE: SUSE-SU-2021:3842-1

Detections

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