CVE-2026-31442 Overview
A memory safety vulnerability has been identified in the Linux kernel's Intel Data Accelerator (IDXD) driver that can result in invalid memory access following a Function Level Reset (FLR). The vulnerability exists in the dmaengine subsystem where a failure to properly nullify deallocated scratch memory during consecutive FLR operations can lead to use of invalid memory pointers.
Critical Impact
This vulnerability could allow an attacker with local access to trigger invalid memory access conditions, potentially leading to system instability, denial of service, or in certain scenarios, information disclosure through memory corruption.
Affected Products
- Linux kernel with IDXD driver enabled
- Systems using Intel Data Accelerator hardware
- Enterprise servers and workstations with Intel accelerator devices
Discovery Timeline
- April 22, 2026 - CVE-2026-31442 published to NVD
- April 23, 2026 - Last updated in NVD database
Technical Details for CVE-2026-31442
Vulnerability Analysis
The vulnerability resides in the Intel Data Accelerator (IDXD) driver within the Linux kernel's DMA engine subsystem. When a Function Level Reset (FLR) is performed on an IDXD device, the driver allocates a scratch memory area to temporarily save device configuration data. Upon successful completion of the first FLR, this scratch area is deallocated but the pointer is not set to NULL.
If a subsequent FLR operation fails to allocate memory for a new scratch area, the driver may inadvertently access the previously freed memory location through the stale pointer. This creates a classic use-after-free scenario where the memory may have been reallocated for other purposes, leading to unpredictable behavior including invalid memory access, data corruption, or system crashes.
Root Cause
The root cause of this vulnerability is improper memory management in the IDXD driver's FLR handling code. Specifically, after the scratch area used during FLR is deallocated, the pointer referencing that memory is not set to NULL. This violates secure coding practices that require cleared pointers after memory deallocation to prevent dangling pointer references.
The fix involves ensuring that the scratch area pointer is always set to NULL after FLR completes, regardless of whether the operation succeeded or failed. This defensive programming approach prevents any subsequent code paths from incorrectly assuming the pointer references valid memory.
Attack Vector
Exploitation of this vulnerability requires local access to a system with the IDXD driver enabled and Intel accelerator hardware present. An attacker would need the ability to trigger Function Level Reset operations on the device, which typically requires elevated privileges or specific access to PCIe device management interfaces.
The attack scenario involves:
- Triggering an initial FLR that completes successfully
- Creating memory pressure conditions to prevent scratch area allocation
- Triggering a second FLR that fails allocation, causing access to freed memory
While exploitation requires specific conditions, systems using Intel accelerators in virtualization environments or shared computing scenarios may be at increased risk where FLR operations are more common.
Detection Methods for CVE-2026-31442
Indicators of Compromise
- Kernel panic or oops messages referencing the IDXD driver or dmaengine subsystem
- Unexpected system crashes during device reset operations
- Memory corruption indicators in system logs related to DMA operations
- Unusual idxd driver errors in dmesg output
Detection Strategies
- Monitor kernel logs for IDXD-related warnings or errors using journalctl -k | grep idxd
- Deploy kernel crash analysis tools to detect memory corruption patterns
- Implement system monitoring for unexpected reboots on systems with Intel accelerators
- Use kernel memory debugging tools like KASAN to detect use-after-free conditions
Monitoring Recommendations
- Enable kernel auditing for device reset events on systems with IDXD hardware
- Configure alerting for kernel module errors in the dmaengine subsystem
- Deploy endpoint detection solutions capable of monitoring kernel-level memory anomalies
- Regularly review dmesg output for IDXD driver initialization and operation errors
How to Mitigate CVE-2026-31442
Immediate Actions Required
- Apply the latest kernel patches from your Linux distribution that address this vulnerability
- If patching is not immediately possible, consider disabling the IDXD driver on affected systems
- Monitor systems with Intel accelerator hardware for signs of exploitation
- Restrict local access to systems running vulnerable kernel versions
Patch Information
The Linux kernel maintainers have released patches to address this vulnerability. The fix ensures that the scratch area pointer is always set to NULL after FLR completes, preventing invalid memory access through stale pointers.
Relevant kernel commits are available through the following references:
Workarounds
- Disable the IDXD driver by adding idxd.legacy_cdev_load=0 to kernel boot parameters
- Blacklist the idxd module by adding blacklist idxd to /etc/modprobe.d/blacklist.conf
- Restrict access to PCIe device management interfaces on affected systems
- Implement additional access controls to limit who can trigger device reset operations
# Configuration example
# Disable IDXD driver via kernel module blacklist
echo "blacklist idxd" | sudo tee /etc/modprobe.d/idxd-blacklist.conf
# Remove the module if currently loaded
sudo modprobe -r idxd
# Verify module is not loaded
lsmod | grep idxd
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
