Ubuntu update for linux-hwe-5.4

Published: 2021-09-16

Risk	Low
Patch available	YES
Number of vulnerabilities	5
CVE-ID	CVE-2020-36311 CVE-2021-22543 CVE-2021-3612 CVE-2021-3653 CVE-2021-3656
CWE-ID	CWE-264 CWE-119 CWE-787
Exploitation vector	Network
Public exploit	Public exploit code for vulnerability #2 is available.
Vulnerable software Subscribe	Ubuntu Operating systems & Components / Operating system linux-image-virtual-hwe-18.04 (Ubuntu package) Operating systems & Components / Operating system package or component linux-image-snapdragon-hwe-18.04 (Ubuntu package) Operating systems & Components / Operating system package or component linux-image-oem-osp1 (Ubuntu package) Operating systems & Components / Operating system package or component linux-image-oem (Ubuntu package) Operating systems & Components / Operating system package or component linux-image-lowlatency-hwe-18.04 (Ubuntu package) Operating systems & Components / Operating system package or component linux-image-generic-lpae-hwe-18.04 (Ubuntu package) Operating systems & Components / Operating system package or component linux-image-generic-hwe-18.04 (Ubuntu package) Operating systems & Components / Operating system package or component linux-image-5.4.0-84-lowlatency (Ubuntu package) Operating systems & Components / Operating system package or component linux-image-5.4.0-84-generic-lpae (Ubuntu package) Operating systems & Components / Operating system package or component linux-image-5.4.0-84-generic (Ubuntu package) Operating systems & Components / Operating system package or component
Vendor	Canonical Ltd.

Security Bulletin

This security bulletin contains information about 5 vulnerabilities.

1) Permissions, Privileges, and Access Controls

EUVDB-ID: #VU55262

Risk: Low

CVSSv3.1: 4.8 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-36311

CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls

Exploit availability: No

Description

The vulnerability allows a local user to perform a denial of service attack.

The vulnerability exists due to an error in arch/x86/kvm/svm/sev.c in Linux kernel, which allows soft lockup by triggering destruction of a large SEV VM (which requires unregistering many encrypted regions).

Mitigation

Update the affected package linux-hwe-5.4 to the latest version.

Vulnerable software versions

Ubuntu: 18.04

linux-image-virtual-hwe-18.04 (Ubuntu package): before 5.4.0.84.94~18.04.75

linux-image-snapdragon-hwe-18.04 (Ubuntu package): before 5.4.0.84.94~18.04.75

linux-image-oem-osp1 (Ubuntu package): before 5.4.0.84.94~18.04.75

linux-image-oem (Ubuntu package): before 5.4.0.84.94~18.04.75

linux-image-lowlatency-hwe-18.04 (Ubuntu package): before 5.4.0.84.94~18.04.75

linux-image-generic-lpae-hwe-18.04 (Ubuntu package): before 5.4.0.84.94~18.04.75

linux-image-generic-hwe-18.04 (Ubuntu package): before 5.4.0.84.94~18.04.75

linux-image-5.4.0-84-lowlatency (Ubuntu package): before 5.4.0-84.94~18.04.1

linux-image-5.4.0-84-generic-lpae (Ubuntu package): before 5.4.0-84.94~18.04.1

linux-image-5.4.0-84-generic (Ubuntu package): before 5.4.0-84.94~18.04.1

External links

http://ubuntu.com/security/notices/USN-5071-2

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

2) Buffer overflow

EUVDB-ID: #VU56018

Risk: Low

CVSSv3.1: 7 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C]

CVE-ID: CVE-2021-22543

CWE-ID: CWE-119 - Memory corruption

Exploit availability: Yes

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a boundary error in Linux kernel when handling VM_IO|VM_PFNMAP vmas in KVM. A local user can can bypass RO checks and cause the pages to get freed while still accessible by the VMM and guest. As a result, an attacker with the ability to start and control a VM to read/write random pages of memory, can trigger memory corruption and execute arbitrary code with elevated privileges.