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Fedora 33 : kernel (2021-7143aca8cb)

high Nessus Plugin ID 146905

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Synopsis

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

Description

The remote Fedora 33 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2021-7143aca8cb advisory.

 - An issue was discovered in the Linux kernel 3.11 through 5.10.16, as used by Xen. To service requests to the PV backend, the driver maps grant references provided by the frontend. In this process, errors may be encountered. In one case, an error encountered earlier might be discarded by later processing, resulting in the caller assuming successful mapping, and hence subsequent operations trying to access space that wasn't mapped. In another case, internal state would be insufficiently updated, preventing safe recovery from the error. This affects drivers/block/xen-blkback/blkback.c. (CVE-2021-26930)

 - An issue was discovered in the Linux kernel 2.6.39 through 5.10.16, as used in Xen. Block, net, and SCSI backends consider certain errors a plain bug, deliberately causing a kernel crash. For errors potentially being at least under the influence of guests (such as out of memory conditions), it isn't correct to assume a plain bug. Memory allocations potentially causing such crashes occur only when Linux is running in PV mode, though. This affects drivers/block/xen-blkback/blkback.c and drivers/xen/xen-scsiback.c.
 (CVE-2021-26931)

 - An issue was discovered in the Linux kernel 3.2 through 5.10.16, as used by Xen. Grant mapping operations often occur in batch hypercalls, where a number of operations are done in a single hypercall, the success or failure of each one is reported to the backend driver, and the backend driver then loops over the results, performing follow-up actions based on the success or failure of each operation. Unfortunately, when running in PV mode, the Linux backend drivers mishandle this: Some errors are ignored, effectively implying their success from the success of related batch elements. In other cases, errors resulting from one batch element lead to further batch elements not being inspected, and hence successful ones to not be possible to properly unmap upon error recovery. Only systems with Linux backends running in PV mode are vulnerable. Linux backends run in HVM / PVH modes are not vulnerable. This affects arch/*/xen/p2m.c and drivers/xen/gntdev.c. (CVE-2021-26932)

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

Solution

Update the affected kernel package.

See Also

https://bodhi.fedoraproject.org/updates/FEDORA-2021-7143aca8cb

Plugin Details

Severity: High

ID: 146905

File Name: fedora_2021-7143aca8cb.nasl

Version: 1.3

Type: local

Agent: unix

Published: 3/1/2021

Updated: 4/12/2021

Supported Sensors: Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5.9

CVSS v2

Risk Factor: Medium

Base Score: 4.6

Temporal Score: 3.4

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

CVSS Score Source: CVE-2021-26930

CVSS v3

Risk Factor: High

Base Score: 7.8

Temporal Score: 6.8

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

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

Vulnerability Information

CPE: p-cpe:/a:fedoraproject:fedora:kernel, cpe:/o:fedoraproject:fedora:33

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

Exploit Ease: No known exploits are available

Patch Publication Date: 2/24/2021

Vulnerability Publication Date: 2/17/2021

Reference Information

CVE: CVE-2021-26930, CVE-2021-26931, CVE-2021-26932