CVE-2025-71301: Linux Kernel Race Condition Vulnerability

CVE-2025-71301 Overview

CVE-2025-71301 is a medium-severity vulnerability in the Linux kernel's Direct Rendering Manager (DRM) Graphics Execution Manager (GEM) shared memory helper subsystem. The flaw resides in the drm_gem_shmem_helper code path used by Kunit tests, where vmap and vunmap operations are invoked without first acquiring the GEM object's reservation lock. The missing lock triggers kernel warnings in drm_gem_shmem_vmap_locked, drm_gem_shmem_pin_locked, drm_gem_shmem_get_pages_locked, and drm_gem_shmem_vunmap_locked. The issue affects the Linux kernel and can lead to availability impact on the local host.

Critical Impact
A local, authenticated user can trigger kernel lock assertion warnings via the DRM SHMEM test path, resulting in availability degradation on affected systems.

Affected Products

Linux Kernel (versions including the affected drm_gem_shmem_helper test code)
Linux distributions shipping the impacted kernel revisions
Systems with DRM Kunit tests enabled in the kernel build

Discovery Timeline

2026-05-08 - CVE-2025-71301 published to NVD
2026-05-14 - Last updated in NVD database

Technical Details for CVE-2025-71301

Vulnerability Analysis

The vulnerability is a locking discipline violation in the DRM GEM SHMEM helper test code. The Kunit tests for the SHMEM helper invoke vmap_locked and vunmap_locked variants without holding the GEM object's dma_resv reservation lock. The locked variants assert that the caller holds the reservation lock, and these assertions fail during test execution.

The failure path emits kernel WARNING messages from drm_gem_shmem_vmap_locked+0x3a3/0x6f0, drm_gem_shmem_pin_locked+0x1fe/0x350, drm_gem_shmem_get_pages_locked+0x23c/0x370, and drm_gem_shmem_vunmap_locked+0x101/0x330. These warnings indicate an inconsistent kernel state related to memory mapping and pinning of GEM-backed buffer objects. The upstream fix wraps the vmap and vunmap test calls in dma_resv_lock and dma_resv_unlock and limits exposure of the new helpers to Kunit only.

Root Cause

The root cause is improper synchronization. Test code invoked functions that require the reservation lock without acquiring that lock first. The kernel's lockdep-style assertions detected the violation and emitted warnings, indicating that internal invariants for GEM SHMEM page management were not honored.

Attack Vector

Exploitation requires local access with low-privilege credentials and no user interaction. The attack vector is constrained to environments where the DRM SHMEM Kunit test surface is reachable. Triggering the condition affects availability on the local host but does not impact confidentiality or integrity. See the upstream commits at git.kernel.org commit e7b7022f, commit cda83b09, and commit 6b953d92 for technical details.

// No verified exploit code is available for this vulnerability.
// Refer to the upstream kernel commits for the patch diff.

Detection Methods for CVE-2025-71301

Indicators of Compromise

Kernel log entries containing WARNING traces from drm_gem_shmem_vmap_locked, drm_gem_shmem_vunmap_locked, drm_gem_shmem_pin_locked, or drm_gem_shmem_get_pages_locked.
Repeated stack traces referencing drivers/gpu/drm/drm_gem_shmem_helper.c at lines 234, 293, 390, or 452.
Unexpected DRM subsystem warnings on systems running kernels with DRM Kunit tests enabled.

Detection Strategies

Monitor dmesg and journalctl -k output for DRM SHMEM helper warning signatures.
Inventory running kernels with uname -r and compare against fixed stable kernel commits.
Audit kernel build configurations for CONFIG_DRM_KUNIT_TEST to identify systems exposing the test path.

Monitoring Recommendations

Forward kernel ring buffer events to a centralized logging platform for DRM warning correlation.
Track kernel version drift across the fleet to verify deployment of patched stable releases.
Alert on recurring WARN_ON traces originating from drm_gem_shmem_helper.c to surface regressions.

How to Mitigate CVE-2025-71301

Immediate Actions Required

Update the Linux kernel to a stable release containing commits e7b7022f11d3, cda83b099f11, or 6b953d92f2f2.
Apply distribution-provided kernel updates as soon as vendor packages become available.
Restrict local access on multi-tenant systems until patches are deployed.

Patch Information

The fix acquires and releases the GEM object's reservation lock around vmap and vunmap calls in the DRM SHMEM Kunit tests. New vmap/vunmap helpers are exported only for Kunit use and are not exposed to regular drivers. Patch references: kernel.org commit e7b7022f, commit cda83b09, and commit 6b953d92.

Workarounds

Disable CONFIG_DRM_KUNIT_TEST in kernel builds where in-kernel DRM tests are not required.
Avoid running DRM Kunit tests on production systems until the patched kernel is installed.
Limit local logon rights to trusted administrators on systems exposing the affected test surface.

bash

# Verify current kernel version and check for the patch
uname -r

# Disable DRM Kunit tests in kernel build configuration
scripts/config --disable CONFIG_DRM_KUNIT_TEST
make olddefconfig