CVE-2024-50280

What it actually does

The flaw triggers an unexpected WARN_ON from flush_work() when device-mapper cache creation fails because an uninitialized delayed_work waker is destroyed in the cache_create() error path (for example on superblock checksum errors).

Why it matters to the business

Failed cache device setups on Linux systems can produce kernel warnings and minor log noise with negligible operational impact; no widespread system instability or data loss is expected.

How an attack unfolds

An attacker or administrator supplies invalid metadata during dm cache creation (such as a corrupted superblock), causing the constructor error path to execute cancel_delayed_work_sync on an uninitialized structure and emit the warning; no code execution or privilege escalation is involved.

How to fix it

Update the Linux kernel to the fixed commit 830b3c68c1fb1e9176028d02ef86f3cf76aa2476 or any later mainline release that includes the change; no configuration changes are required.

How to confirm the fix worked

Confirm the fix commit is present in the running kernel source tree and reproduce the cache creation failure steps to verify that the flush_work warning no longer appears.

Typical attack path

1. Create backing linear devices for cmeta, cdata, and corig via dmsetup
2. Corrupt the cache metadata superblock
3. Issue dmsetup create for the cache target with the malformed metadata
4. Trigger cache_ctr error handling that reaches the uninitialized delayed_work flush

How to detect it

Search kernel logs for the string "WARNING: CPU" combined with "__flush_work" and references to workqueue or dm cache error paths around the time of device-mapper cache creation attempts.

What your security team should do

• Upgrade affected kernels to a version containing commit 830b3c68c1fb1e9176028d02ef86f3cf76aa2476
• Review dm cache setup scripts for error-handling robustness
• Monitor kernel logs for workqueue flush warnings during device-mapper operations