CVE-2024-41073: Linux Kernel Use-After-Free Vulnerability

CVE-2024-41073 Overview

A Double Free vulnerability has been discovered in the Linux kernel's NVMe (Non-Volatile Memory Express) driver subsystem. The flaw occurs when a discard request needs to be retried, and that retry fails before a new special payload is added. This condition results in a double free of the special payload memory, which can lead to memory corruption and potential privilege escalation on affected systems.

Critical Impact

Local attackers with low privileges can exploit this double free condition to potentially corrupt kernel memory, leading to privilege escalation or denial of service on systems utilizing NVMe storage devices.

Affected Products

• Linux Kernel (multiple versions)
• Debian Linux 11.0

Discovery Timeline

• 2024-07-29 - CVE-2024-41073 published to NVD
• 2026-01-14 - Last updated in NVD database

Technical Details for CVE-2024-41073

Vulnerability Analysis

This vulnerability exists within the NVMe driver's handling of discard requests in the Linux kernel. The NVMe subsystem uses special payload structures to manage certain types of I/O operations, including discard (TRIM) commands that inform the storage device about blocks no longer in use.

The vulnerability stems from improper memory management during the retry logic for failed discard operations. When a discard request initially fails and the kernel attempts to retry the operation, there exists a race condition where the original special payload may be freed while still referenced. If the retry subsequently fails before a new special payload can be allocated and attached, the cleanup code attempts to free the already-deallocated memory, resulting in a double free condition.

Double free vulnerabilities (CWE-415) in kernel context are particularly dangerous because they can corrupt the kernel's memory allocator metadata. An attacker who can trigger this condition reliably may be able to manipulate heap structures to achieve arbitrary code execution with kernel privileges.

Root Cause

The root cause is the failure to clear the RQF_SPECIAL_LOAD request flag when a request is cleaned up after a failed retry attempt. This flag indicates that a special payload is attached to the request, and when it remains set incorrectly, the kernel's cleanup routines assume a payload exists and attempt to free it again.

The fix involves clearing the RQF_SPECIAL_LOAD flag during request cleanup, ensuring that subsequent operations correctly understand the state of any attached payloads and prevent double deallocation.

Attack Vector

The attack requires local access to the system with the ability to perform NVMe I/O operations. An attacker with low-level privileges can attempt to trigger the vulnerability through the following attack surface:

1. Initiate discard operations on NVMe storage devices
2. Induce failure conditions that cause discard retries (potentially through resource exhaustion or timing manipulation)
3. Exploit the race window between retry failure and payload reallocation
4. Leverage the resulting memory corruption for privilege escalation

The exploitation complexity is increased by the need to win a race condition, but the local attack vector and low privilege requirements make this vulnerability accessible to authenticated local users.

Detection Methods for CVE-2024-41073

Indicators of Compromise

• Unexpected kernel panics or system crashes related to NVMe subsystem operations
• Kernel log messages indicating memory corruption in nvme or blk-mq subsystems
• SLUB/SLAB allocator warnings about double-free or use-after-free conditions
• Unusual patterns of NVMe discard operations in system logs

Detection Strategies

• Monitor kernel logs for memory subsystem errors using dmesg or syslog analysis
• Deploy kernel runtime verification tools like KASAN (Kernel Address Sanitizer) to detect double-free conditions
• Implement audit rules to monitor for suspicious NVMe device interactions
• Use SentinelOne Singularity Platform for real-time kernel-level threat detection

Monitoring Recommendations

• Enable kernel debug options for memory allocation tracking in development/test environments
• Configure system monitoring to alert on kernel oops or panic events
• Review NVMe driver logs for retry patterns that could indicate exploitation attempts
• Implement centralized log aggregation to correlate events across multiple systems

How to Mitigate CVE-2024-41073

Immediate Actions Required

• Update Linux kernel to patched versions as indicated in vendor advisories
• Apply Debian security updates for affected Debian 11 systems
• Prioritize patching for systems with NVMe storage that are accessible to untrusted local users
• Consider restricting NVMe device access permissions where feasible

Patch Information

The Linux kernel maintainers have released patches to address this vulnerability. The fix clears the RQF_SPECIAL_LOAD flag when the request is cleaned, preventing the double free condition. Multiple kernel stable branches have received patches:

• Kernel Git Commit 1b9fd1265fac
• Kernel Git Commit 882574942a9b
• Kernel Git Commit ae84383c96d6
• Kernel Git Commit c5942a14f795
• Kernel Git Commit e5d574ab37f5
• Kernel Git Commit f3ab45aacd25

Debian users should refer to the Debian LTS Security Announcement for package updates.

Workarounds

• Restrict local user access to systems with NVMe storage until patching is complete
• Limit unprivileged user access to NVMe device nodes through permission adjustments
• Consider temporarily disabling discard/TRIM operations via mount options (nodiscard) as a short-term mitigation
• Deploy additional access controls and monitoring for systems that cannot be immediately patched

# Temporary workaround: Mount filesystems with nodiscard option
# Edit /etc/fstab to add nodiscard mount option for NVMe devices
# Example entry:
# /dev/nvme0n1p1 /data ext4 defaults,nodiscard 0 2

# Remount existing filesystems without discard
mount -o remount,nodiscard /mount/point