CVE-2025-40302

What it actually does

The vulnerability allows vb2_ioctl_remove_bufs to manipulate the videobuf2 queue's internal buffer list while legacy fileio mode is active, overwriting pointers relied upon by subsequent read/write operations and creating a race condition that can corrupt queue state.

Why it matters to the business

Systems performing media capture or streaming may experience kernel instability, crashes, or unpredictable behavior in video pipelines, potentially disrupting workloads on affected Linux distributions until kernels are updated.

How an attack unfolds

An attacker with local access triggers the remove_bufs ioctl concurrently with active legacy fileio operations on a videobuf2 queue, exploiting the missing guard to corrupt internal pointers and induce a crash or memory corruption.

How to fix it

Upgrade to a kernel containing commit a6a493b985bfffac097a4e1be09f98b27729dca8 or apply the equivalent Ubuntu package update 2.4.2-3ubuntu0.1~esm2 for affected releases; rebuild and reboot with the patched kernel.

How to confirm the fix worked

Confirm the running kernel contains the referenced commit or package version; test that vb2_ioctl_remove_bufs returns an error when legacy fileio is active and verify no pointer corruption occurs under concurrent access.

Typical attack path

1. Locate a process or driver using videobuf2 with legacy fileio active
2. Issue vb2_ioctl_remove_bufs while fileio operations are in progress
3. Trigger pointer overwrite between read/write calls to corrupt queue state
4. Cause denial of service via kernel panic or exploitable memory corruption

How to detect it

Review kernel logs for videobuf2 queue corruption warnings or oops during media ioctl sequences; correlate process activity performing concurrent remove_bufs and fileio calls on video devices.

What your security team should do

• Prioritize kernel upgrades on all systems using videobuf2 media drivers
• Disable legacy fileio where possible until patches are deployed
• Monitor vendor advisories for backported fixes in stable kernels