CVE-2026-31390 Overview
A memory leak vulnerability has been identified in the Linux kernel's Direct Rendering Manager (DRM) subsystem, specifically within the Intel Xe graphics driver. The vulnerability occurs in the xe_vm_madvise_ioctl function when the check_bo_args_are_sane() validation fails, causing allocated resources to not be properly freed. This results in a memory leak that could lead to resource exhaustion over time.
Critical Impact
Repeated triggering of this vulnerability through failed validation attempts could lead to kernel memory exhaustion, potentially causing system instability or denial of service conditions.
Affected Products
- Linux Kernel with Intel Xe DRM driver
- Systems utilizing Intel discrete graphics with the Xe driver
- Linux distributions shipping affected kernel versions
Discovery Timeline
- 2026-04-03 - CVE CVE-2026-31390 published to NVD
- 2026-04-07 - Last updated in NVD database
Technical Details for CVE-2026-31390
Vulnerability Analysis
This vulnerability is classified as a Memory Leak within the Linux kernel's DRM subsystem. The issue resides in the xe_vm_madvise_ioctl function, which handles memory advice operations for virtual memory management in the Intel Xe graphics driver. When user-supplied buffer object arguments fail the check_bo_args_are_sane() validation, the function's error handling path does not properly release previously allocated virtual memory area (VMA) resources before returning.
The lack of proper cleanup in this specific error path means that each failed ioctl call with invalid arguments will leak kernel memory. While individual leaks may be small, an attacker or errant application repeatedly triggering this condition could gradually exhaust available kernel memory.
Root Cause
The root cause of this vulnerability is an incomplete error handling implementation in the xe_vm_madvise_ioctl function. When the validation function check_bo_args_are_sane() returns a failure, the original code path returned immediately without jumping to the appropriate cleanup label that would free the allocated VMA structures. This is a common programming pattern error in kernel code where resources are allocated early in a function but not all error paths properly release them.
Attack Vector
The attack vector for this vulnerability involves a local user with access to the graphics device making repeated ioctl calls with intentionally malformed buffer object arguments. Since this is a kernel driver vulnerability accessible through the DRM subsystem:
- An attacker requires local access to the system with permissions to interact with the graphics device
- The attacker crafts ioctl requests that pass initial checks but fail the check_bo_args_are_sane() validation
- Each failed request leaks kernel memory
- Repeated exploitation over time can exhaust kernel memory resources, leading to denial of service
The vulnerability requires local access and cannot be exploited remotely. The fix introduces a new free_vmas cleanup label that ensures proper resource deallocation when validation fails.
Detection Methods for CVE-2026-31390
Indicators of Compromise
- Gradual increase in kernel memory usage without corresponding user-space allocation
- Slab memory exhaustion warnings in kernel logs related to DRM or Xe driver allocations
- System slowdowns or out-of-memory conditions in systems using Intel Xe graphics
Detection Strategies
- Monitor kernel memory statistics using tools like /proc/meminfo and /proc/slabinfo for unusual growth in DRM-related allocations
- Enable kernel memory leak detection tools such as kmemleak during testing environments
- Audit system calls to the DRM ioctl interface for patterns of repeated failed madvise operations
Monitoring Recommendations
- Implement system monitoring for kernel memory usage trends on systems with Intel Xe graphics drivers
- Configure alerts for kernel memory exhaustion warnings in system logs
- Review audit logs for unusual patterns of DRM ioctl activity from non-privileged processes
How to Mitigate CVE-2026-31390
Immediate Actions Required
- Apply the latest kernel security patches that include the fix for this vulnerability
- Update to a patched kernel version that includes commit 29bd06faf727a4b76663e4be0f7d770e2d2a7965 or its backports
- Consider restricting access to the graphics device for untrusted users if patching is delayed
Patch Information
The Linux kernel maintainers have addressed this vulnerability through multiple commits across stable kernel branches. The fix ensures that when check_bo_args_are_sane() validation fails, execution jumps to the new free_vmas cleanup label to properly release allocated resources before returning.
Patch commits are available at:
Workarounds
- Limit access to the Intel Xe graphics device to trusted users only by adjusting device permissions
- Monitor system memory usage and schedule periodic reboots if patching cannot be immediately applied
- Consider temporarily blacklisting the xe kernel module if Intel Xe graphics functionality is not required
# Restrict graphics device access to trusted groups only
chmod 660 /dev/dri/card*
chgrp video /dev/dri/card*
# Alternatively, blacklist xe module if not required (requires reboot)
echo "blacklist xe" >> /etc/modprobe.d/blacklist-xe.conf
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
