CVE-2022-1419

What it actually does

Use-after-free in the Linux kernel DRM VGEM driver where DRM_IOCTL_MODE_DESTROY_DUMB can decrement the reference count on a drm_vgem_gem_object created by vgem_gem_dumb_create, allowing concurrent access to the freed object.

Why it matters to the business

Local attackers on affected Linux systems can potentially escalate privileges to gain full control, risking system compromise, data theft, or persistence on servers, workstations, and embedded devices using the vulnerable kernel.

How an attack unfolds

An attacker with local access triggers a race condition by calling DRM_IOCTL_MODE_DESTROY_DUMB to free a gem object while vgem_gem_dumb_create is still accessing it, leading to a use-after-free that can be leveraged for arbitrary code execution in kernel context.

How to fix it

Update the Linux kernel to a version containing commit 7111951b8d4973bda27ff663f2cf18b663d15b48 which addresses the reference counting issue in the VGEM driver; rebuild and reboot with the patched kernel.

How to confirm the fix worked

Verify the running kernel contains commit 7111951b8d4973bda27ff663f2cf18b663d15b48 or later equivalent fix; test that concurrent ioctl sequences no longer trigger use-after-free conditions via kernel memory debugging tools.

Typical attack path

1. Obtain local user access on a vulnerable Linux system
2. Open the DRM device and allocate a dumb buffer via vgem_gem_dumb_create
3. Concurrently invoke DRM_IOCTL_MODE_DESTROY_DUMB to drop the reference count
4. Trigger access to the now-freed drm_vgem_gem_object structure
5. Exploit the resulting use-after-free for kernel memory corruption and privilege escalation

How to detect it

Review kernel logs for use-after-free warnings or oops related to vgem_gem_dumb_create and DRM_IOCTL_MODE_DESTROY_DUMB; inspect for anomalous local process activity attempting DRM ioctls on VGEM devices.

What your security team should do

• Prioritize kernel updates on all internet-facing and multi-user Linux systems
• Apply the fix from commit 7111951b8d4973bda27ff663f2cf18b663d15b48 across distributions
• Restrict local user access where possible until patches are deployed
• Monitor for new exploit code targeting this use-after-free