PT-2021-4256 · Linux+3 · Linux Kernel+3

Naohiro Aota · Published 2021-07-07 · Updated 2023-05-17 · CVE-2021-38203

Positive Technologies (AI Summary)

CVSS v3.1

5.5

Medium

Base vector

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

Name of the Vulnerable Software and Affected Versions Linux kernel versions prior to 5.13.4

Description The issue is related to the btrfs implementation in the Linux kernel, which can lead to a denial of service due to uncontrolled memory allocation. This can occur when there is a shortage of free space in the system space info, and processes trigger the allocation of new system chunks. As a result, an attacker can cause a deadlock.

Recommendations For Linux kernel versions prior to 5.13.4, update to version 5.13.4 or later to resolve the issue. As a temporary workaround, consider restricting system chunk allocation during times of low free space in the system space info to minimize the risk of exploitation.

Exploit

Fix

DoS

Improper Locking

Allocation of Resources Without Limits

Weakness Enumeration

CWE-667

CWE-770

Related Identifiers

ALT-PU-2021-2284

ALT-PU-2021-2486

ALT-PU-2021-2616

ALT-PU-2021-3563

ALT-PU-2021-3573

ALT-PU-2022-1240

ALT-PU-2022-1419

ALT-PU-2022-1421

ALT-PU-2023-1814

AZL-6587

BDU:2021-04864

CVE-2021-38203

USN-5096-1

Affected Products

Alt Linux

Linuxmint

Linux Kernel

Ubuntu

References · 36

• 🔥 https://github.com/torvalds/linux/commit/1cb3db1cf383a3c7dbda1aa0ce748b0958759947 · Exploit
• https://ubuntu.com/security/notices/USN-5096-1 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2021-38203 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2021-38203 · Security Note
• https://osv.dev/vulnerability/AZL-6587 · Vendor Advisory
• https://ubuntu.com/security/CVE-2021-38160 · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2021-38203 · Security Note
• https://osv.dev/vulnerability/UBUNTU-CVE-2021-38203 · Vendor Advisory
• https://ubuntu.com/security/CVE-2021-38204 · Vendor Advisory
• https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.13.4 · Vendor Advisory
• https://ubuntu.com/security/CVE-2021-35477 · Vendor Advisory
• https://ubuntu.com/security/CVE-2021-37159 · Vendor Advisory
• https://bdu.fstec.ru/vul/2021-04864 · Security Note
• https://ubuntu.com/security/CVE-2021-34556 · Vendor Advisory
• https://ubuntu.com/security/CVE-2021-3732 · Vendor Advisory