PT-2025-7948 · Linux+3 · Linux Kernel+3

Zhihao Cheng · Published 2025-02-26 · Updated 2025-05-21 · CVE-2021-47637

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 deadlock issue in the Linux kernel has been identified, specifically in the ubifs file system. This occurs when concurrent rename whiteout and inode writeback processes are executed, causing tasks to hang. The issue arises from the locking mechanism used by the ubifs rename and ubifs write inode functions, which can lead to a deadlock situation. The problem is triggered by the SYS renameat2 system call when used with the RENAME WHITEOUT flag, and it can be reproduced by consuming available space before the kernel performs budgeting for the whiteout operation.

Recommendations To resolve this issue, apply the fix that budgets whiteout space before locking ubifs inodes. This fix also corrects an error handling path in the whiteout budget, ensuring proper recovery of directory i size and unlocking of ubifs inodes. At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Exploit

Improper Locking

Weakness Enumeration

CWE-667

Related Identifiers

CVE-2021-47637

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 · 1336

• 🔥 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://cve.org/CVERecord?id=CVE-2021-47637 · Security Note
• https://osv.dev/vulnerability/CVE-2021-47637 · Vendor Advisory
• https://git.kernel.org/stable/c/70e9090acc32348cedc5def0cd6d5c126efc97b9 · Patch
• https://osv.dev/vulnerability/SUSE-SU-2025:1027-1 · Vendor Advisory
• https://git.kernel.org/stable/c/8b278c8dcfb565cb65eceb62a38cbf7a7c326db5 · Patch
• https://osv.dev/vulnerability/UBUNTU-CVE-2021-47637 · Vendor Advisory
• https://osv.dev/vulnerability/SUSE-SU-2025:1241-1 · Vendor Advisory
• https://git.kernel.org/stable/c/9dddc8211430fb851ddf0b168e3a00c6f66cc185 · Patch
• https://osv.dev/vulnerability/SUSE-SU-2025:1176-1 · Vendor Advisory