CVE-2026-31441: Linux Kernel Memory Leak Vulnerability

CVE-2026-31441 Overview

A memory leak vulnerability has been discovered in the Linux kernel's IDXD (Intel Data Accelerator Driver) subsystem. The flaw occurs in the idxd_wq_disable_cleanup() function when a workqueue is reset. The function prematurely sets the workqueue type to NONE before its associated resources are properly released, leading to memory leaks that can impact system stability over time.

Critical Impact

This vulnerability can lead to gradual memory exhaustion on systems utilizing Intel Data Accelerators, potentially causing system instability or denial of service conditions during workqueue reset operations.

Affected Products

• Linux kernel with IDXD (Intel Data Accelerator Driver) support enabled
• Systems utilizing Intel Data Streaming Accelerator (DSA) or Intel Analytics Accelerator (IAX)
• Multiple Linux kernel stable branches (see patch commits for specific versions)

Discovery Timeline

• 2026-04-22 - CVE CVE-2026-31441 published to NVD
• 2026-04-23 - Last updated in NVD database

Technical Details for CVE-2026-31441

Vulnerability Analysis

The vulnerability exists within the DMA engine subsystem of the Linux kernel, specifically in the IDXD driver responsible for managing Intel Data Accelerators. When a workqueue undergoes a reset operation, the idxd_wq_disable_cleanup() function is invoked to clean up workqueue resources. However, a logic flaw in this function causes it to set the workqueue type to NONE prematurely—before the workqueue's allocated resources have been properly freed.

In the IDXD driver architecture, setting a workqueue type to NONE signals to other driver components that the workqueue is empty and all its resources have been released. When this flag is set too early, subsequent cleanup routines may skip resource deallocation, believing the work has already been completed. This results in orphaned memory allocations that persist until the system is rebooted.

Root Cause

The root cause is an incorrect ordering of operations in the idxd_wq_disable_cleanup() function. The workqueue type is set to NONE at the beginning of the cleanup sequence rather than at the end after all resources have been properly released. This premature state change causes a disconnect between the workqueue's reported state and its actual resource allocation status, leading to memory being leaked on each workqueue reset operation.

Attack Vector

The attack vector for this vulnerability is local. An attacker with the ability to trigger workqueue reset operations on a system with IDXD enabled could repeatedly trigger the memory leak condition. Over time, this could exhaust available system memory, leading to denial of service. In shared computing environments or containerized workloads utilizing Intel accelerators, this could impact the stability of co-located workloads.

The vulnerability does not require elevated privileges to trigger in environments where unprivileged users have access to IDXD workqueue operations, though typical deployments restrict such access to privileged processes or specific user groups.

Detection Methods for CVE-2026-31441

Indicators of Compromise

• Gradual increase in kernel memory usage over time without corresponding application memory growth
• Memory allocation failures or out-of-memory conditions on systems with IDXD workloads
• System logs showing repeated workqueue reset events in the IDXD driver
• Unexplained system performance degradation on servers utilizing Intel Data Accelerators

Detection Strategies

• Monitor kernel memory allocation statistics using tools like /proc/meminfo and compare against baseline values
• Implement alerting for unusual memory growth patterns on systems running IDXD workloads
• Review kernel logs for IDXD-related reset events using dmesg | grep -i idxd
• Deploy memory leak detection tools such as kmemleak to identify orphaned allocations in the kernel

Monitoring Recommendations

• Establish baseline memory usage metrics for systems with IDXD enabled and alert on deviations
• Implement periodic memory audits using kernel debugging facilities
• Monitor workqueue reset frequency through IDXD driver statistics
• Configure automated alerts for sustained memory growth without corresponding workload increases

How to Mitigate CVE-2026-31441

Immediate Actions Required

• Apply the available kernel patches from the Linux stable kernel branches
• Schedule system reboots to reclaim leaked memory on affected systems
• Consider temporarily disabling IDXD workqueue functionality if the vulnerability is being actively exploited
• Update to a patched kernel version as soon as possible

Patch Information

The Linux kernel maintainers have released patches to address this vulnerability across multiple stable branches. The fix ensures that the workqueue type is only set to NONE after all associated resources have been properly released.

Patch commits are available from the kernel.org git repository:

• Linux Kernel Commit 0c3d3ac57e3c
• Linux Kernel Commit 39c1504e0e76
• Linux Kernel Commit 54d77cc0c40c
• Linux Kernel Commit a16098a2f0c1
• Linux Kernel Commit a9e7815d3862
• Linux Kernel Commit d9cfb5193a04

Workarounds

• Minimize workqueue reset operations where possible until patches can be applied
• Implement scheduled reboots to periodically reclaim leaked memory
• Monitor memory usage and trigger preventive reboots when thresholds are approached
• Consider disabling the IDXD driver module (idxd) if Intel Data Accelerator functionality is not required

# Check if IDXD module is loaded
lsmod | grep idxd

# Temporarily disable IDXD module if not required (requires root)
modprobe -r idxd

# Blacklist IDXD module to prevent loading on boot
echo "blacklist idxd" >> /etc/modprobe.d/blacklist-idxd.conf