CVE-2024-53164: Linux Kernel DOS Vulnerability

CVE-2024-53164 Overview

CVE-2024-53164 is a vulnerability in the Linux kernel's network scheduler (net/sched) subsystem related to improper ordering of queue length (qlen) adjustments. The flaw occurs when changes to sch->q.qlen are not properly synchronized with calls to qdisc_tree_reduce_backlog(), which can result in parent qdiscs not being notified when a child qdisc is about to become empty. This race condition in the traffic control subsystem can lead to system instability and denial of service conditions.

Critical Impact

Local attackers with low privileges can exploit this vulnerability to cause a denial of service condition by triggering improper queue length handling in the kernel's network scheduler, potentially leading to system crashes or network subsystem failures.

Affected Products

• Linux Kernel (multiple versions)
• Linux Kernel 6.13-rc1
• Debian Linux (LTS releases)

Discovery Timeline

• December 27, 2024 - CVE-2024-53164 published to NVD
• November 3, 2025 - Last updated in NVD database

Technical Details for CVE-2024-53164

Vulnerability Analysis

The vulnerability resides in the Linux kernel's traffic control (tc) subsystem, specifically in how queue discipline (qdisc) operations handle backlog reduction. When a qdisc processes packets and needs to adjust its queue length, the qdisc_tree_reduce_backlog() function is called to propagate these changes up the qdisc hierarchy to parent schedulers.

The root cause is a timing issue where the queue length (sch->q.qlen) modification occurs after the call to qdisc_tree_reduce_backlog() rather than before it. This incorrect ordering means that when a child qdisc is about to become empty, the parent qdisc may not receive proper notification of this state change. The parent qdisc relies on accurate queue length information to make scheduling decisions, and stale or incorrect values can lead to inconsistent internal state.

This vulnerability requires local access to exploit, as an attacker would need the ability to configure or interact with network qdiscs on the system. The impact is primarily availability-focused, as exploitation could cause the network subsystem to enter an inconsistent state, potentially leading to kernel panics or network connectivity failures.

Root Cause

The vulnerability stems from incorrect code ordering in the qdisc tree management logic. The qlen adjustment must occur before qdisc_tree_reduce_backlog() is called because that function uses the current queue length to determine whether to notify parent qdiscs about state changes. When the adjustment happens afterward, the function operates on stale data, failing to properly propagate the "becoming empty" notification to parent schedulers.

Attack Vector

The attack vector is local, requiring an authenticated user with low privileges to interact with the network scheduler subsystem. An attacker could potentially trigger this vulnerability by manipulating traffic control configurations or generating specific network traffic patterns that cause the race condition to manifest. This could be achieved through standard networking tools that interact with the kernel's qdisc subsystem.

The exploitation scenario involves creating conditions where the qdisc_tree_reduce_backlog() function is called with outdated queue length information, causing parent qdiscs to maintain incorrect state and potentially leading to resource exhaustion or system instability.

Detection Methods for CVE-2024-53164

Indicators of Compromise

• Unexpected kernel panics or oops messages referencing net/sched or qdisc components
• Network subsystem failures or connectivity issues without apparent external cause
• System log entries indicating qdisc-related errors or warnings
• Unusual traffic control behavior or scheduler inconsistencies

Detection Strategies

• Monitor kernel logs (dmesg, /var/log/kern.log) for qdisc-related error messages or stack traces
• Implement kernel crash dump analysis to identify net/sched subsystem crashes
• Deploy SentinelOne Singularity Platform for real-time kernel-level threat detection and behavioral analysis
• Use auditd to monitor traffic control configuration changes via tc commands

Monitoring Recommendations

• Enable kernel crash reporting mechanisms (kdump, netconsole) to capture diagnostic data
• Monitor system stability metrics and correlate with network subsystem activity
• Configure alerting for unexpected kernel restarts or network service failures
• Review traffic control configurations periodically for unauthorized modifications

How to Mitigate CVE-2024-53164

Immediate Actions Required

• Update the Linux kernel to a patched version that includes the ordering fix
• Review and audit current qdisc configurations for potential attack surface reduction
• Limit local user access to traffic control utilities where not required
• Apply vendor-specific patches from distribution security advisories

Patch Information

The Linux kernel maintainers have released patches to address this vulnerability by correcting the ordering of qlen adjustments relative to qdisc_tree_reduce_backlog() calls. Multiple stable kernel branches have been patched with the following commits:

• Kernel Commit 33db36b3c53d
• Kernel Commit 44782565e1e6
• Kernel Commit 489422e2beff
• Kernel Commit 5e473f462a16
• Kernel Commit 5eb7de8cd58e
• Kernel Commit 97e13434b5da
• Kernel Commit e3e54ad9eff8

Debian users should refer to the Debian LTS Security Announcements for distribution-specific package updates.

Workarounds

• Restrict access to traffic control utilities (tc) to authorized administrators only
• Minimize qdisc hierarchy complexity where possible to reduce potential attack surface
• Implement network namespace isolation to limit qdisc configuration scope
• Consider disabling advanced qdisc features if not required for operations

# Restrict tc utility access to root only
chmod 750 /sbin/tc

# Monitor qdisc configuration changes
auditctl -w /sbin/tc -p x -k traffic_control

# Check current kernel version for vulnerability status
uname -r