PT-2024-11177 · Linux · Linux Kernel

Maxim Mikityanskiy + 1 · Published 2021-06-04 · Updated 2025-01-07 · CVE-2021-47125

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 refcount leak issue has been identified in the Linux kernel, specifically in the htb parent to leaf offload function. The commit ae81feb7338c, which aimed to fix a NULL pointer dereference bug, was found to be incorrect. The htb graft helper function properly handles the case when new q is NULL, but skipping this call creates an inconsistency where dev queue->qdisc points to the old qdisc, while cl->parent->leaf.q points to the new one, which can be noop qdisc if new q is NULL. This inconsistency can lead to refcount leaks. The correct fix involves adding a NULL pointer check to protect qdisc refcount inc inside htb parent to leaf offload.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Weakness Enumeration

CWE-402

Related Identifiers

BDU:2025-07282

CVE-2021-47125

Affected Products

Linux Kernel

References · 14

• https://nvd.nist.gov/vuln/detail/CVE-2021-47125 · Security Note
• https://osv.dev/vulnerability/UBUNTU-CVE-2021-47125 · Vendor Advisory
• https://git.kernel.org/stable/c/2411c02d03892a5057499f8102d0cc1e0f852416 · Patch
• https://bdu.fstec.ru/vul/2025-07282 · Security Note
• https://osv.dev/vulnerability/CVE-2021-47125 · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2021-47125 · Security Note
• https://git.kernel.org/stable/c/944d671d5faa0d78980a3da5c0f04960ef1ad893 · Patch
• https://ubuntu.com/security/CVE-2021-47125 · Vendor Advisory
• https://git.kernel.org/linus/944d671d5faa0d78980a3da5c0f04960ef1ad893 · Note
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-47125 · Note
• https://t.me/cvenotify/106625 · Telegram Post
• https://lore.kernel.org/linux-cve-announce/2024031511-CVE-2021-47125-9c33@gregkh · Note
• https://twitter.com/CVEnew/status/1768738333570576405 · Twitter Post
• https://kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.12.10 · Note