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CVE-2025-38477

Updated on 28 Jul 2025

Severity

4.7 Medium severity

Details

CVSS score
4.7
CVSS vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE ID
Links
NISTCIRCLRHELUbuntu

Overview

About vulnerability

In the Linux kernel, the following vulnerability has been resolved:

net/sched: sch_qfq: Fix race condition on qfq_aggregate

A race condition can occur when ‘agg’ is modified in qfq_change_agg (called during qfq_enqueue) while other threads access it concurrently. For example, qfq_dump_class may trigger a NULL dereference, and qfq_delete_class may cause a use-after-free.

This patch addresses the issue by:

  1. Moved qfq_destroy_class into the critical section.

  2. Added sch_tree_lock protection to qfq_dump_class and qfq_dump_class_stats.

Details

Affected product:
AlmaLinux 9.2 ESU , CentOS 6 ELS , CentOS 7 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , CloudLinux 7 ELS , Oracle Linux 6 ELS , Oracle Linux 7 ELS , RHEL 7 ELS , TuxCare 9.6 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS
Affected packages:
linux-hwe @ 4.15.0 (+15 more)

In the Linux kernel, the following vulnerability has been resolved:

net/sched: sch_qfq: Fix race condition on qfq_aggregate

A race condition can occur when ‘agg’ is modified in qfq_change_agg (called during qfq_enqueue) while other threads access it concurrently. For example, qfq_dump_class may trigger a NULL dereference, and qfq_delete_class may cause a use-after-free.

This patch addresses the issue by:

  1. Moved qfq_destroy_class into the critical section.

  2. Added sch_tree_lock protection to qfq_dump_class and qfq_dump_class_stats.

Fixes