PT-2025-7949 · Linux+3 · Linux Kernel+3

Zhihao Cheng · Published 2025-02-26 · Updated 2025-05-21 · CVE-2021-47638

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 (affected versions not specified)

Description A double-free issue has been identified in the Linux kernel, specifically in the ubifs module. The problem occurs when the rename whiteout operation fails due to a space budget issue, causing the whiteout ui->data to be freed twice. This is confirmed by KASAN reports, which indicate a double-free or invalid-free error in ubifs free inode. The issue arises from the rename whiteout process, where whiteout ui->data is allocated and then freed, but also freed again in ubifs free inode. The estimated number of potentially affected devices is not provided.

Recommendations To resolve the issue, let ubifs free inode() free whiteout ui->data. Additionally, remove the unused assignment whiteout ui->data len = 0, as it is not needed in the ubifs evict inode() process.

Exploit

Fix

Double Free

Weakness Enumeration

CWE-415

Related Identifiers

CVE-2021-47638

SUSE-SU-2025:1027-1

SUSE-SU-2025:1176-1

SUSE-SU-2025:1183-1

SUSE-SU-2025:1241-1

SUSE-SU-2025_1027-1

SUSE-SU-2025_1241-1

Affected Products

Astra Linux

Linux Kernel

Red Os

Suse

References · 1337

• 🔥 https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/linux/local/cve_2022_0995_watch_queue.rb · Exploit
• 🔥 https://github.com/qazbnm456/awesome-cve-poc/blob/master/CVE-2017-5753.md · Exploit
• 🔥 https://github.com/Bonfee/CVE-2022-0995 · Exploit
• 🔥 https://github.com/TurtleARM/CVE-2023-0179-PoC · Exploit
• 🔥 https://github.com/H4K6/CVE-2023-0179-PoC · Exploit
• 🔥 https://github.com/EdwardOwusuAdjei/Spectre-PoC · Exploit
• https://osv.dev/vulnerability/SUSE-SU-2025:1027-1 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2021-47638 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2021-47638 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2021-47638 · Vendor Advisory
• https://git.kernel.org/stable/c/2b3236ecf96db7af5836e1366ce39ace8ce832fa · Patch
• https://git.kernel.org/stable/c/40a8f0d5e7b3999f096570edab71c345da812e3e · Patch
• https://git.kernel.org/stable/c/14276d38c89a170363e90b6ac0a53c3cf61b87fc · Patch
• https://osv.dev/vulnerability/UBUNTU-CVE-2021-47638 · Vendor Advisory
• https://osv.dev/vulnerability/SUSE-SU-2025:1241-1 · Vendor Advisory