CVE-2022-48981

What it actually does

The drm_gem_shmem_mmap function releases a reference it does not own on a GEM object, causing the object to be freed while still referenced and enabling a later use-after-free in the kernel.

Why it matters to the business

Kernel memory corruption can lead to system crashes, denial of service, or potential privilege escalation on affected Linux systems, increasing operational downtime and security risk especially where graphics subsystems are active.

How an attack unfolds

An attacker with local access triggers the error path in drm_gem_shmem_mmap to drop the reference prematurely, then reuses the freed GEM object in subsequent operations to achieve use-after-free for code execution or information disclosure.

How to fix it

Update the Linux kernel to a version containing commit 3a3f9dd8a706af569c5581b20dcfeff91a43b9d9 or later; apply the fix to any dependent packages such as lara-zeus/artemis by updating to the commit-pinned release.

How to confirm the fix worked

Verify the kernel source contains the referenced commit, confirm drm_gem_shmem_mmap no longer performs the erroneous put, and test mmap error paths do not result in premature object release.

Typical attack path

1. Obtain local access on a vulnerable Linux system
2. Trigger mmap operations on DRM GEM shared memory objects that hit the error path
3. Reuse the prematurely freed object to corrupt kernel memory
4. Escalate privileges or execute arbitrary kernel code

How to detect it

Inspect kernel logs for use-after-free warnings or oops involving drm_gem_shmem or GEM objects; correlate with processes performing unusual mmap calls on DRM devices.

What your security team should do

• Prioritize kernel updates on systems exposing DRM/graphics interfaces
• Monitor for local privilege-escalation attempts targeting kernel memory objects
• Apply the specific commit 3a3f9dd8a706af569c5581b20dcfeff91a43b9d9 to affected packages
• Review and restrict untrusted local code execution where possible