CVE-2024-47739

What it actually does

Integer wrap-around in padata seq_nr handling causes objects with overflowed sequence numbers to be incorrectly sorted ahead of existing entries in the reorder list, preventing padata_find_next from matching seq_nr and processed state and resulting in a permanent deadlock during serialization.

Why it matters to the business

Systems performing sustained high-volume parallel data serialization may experience sudden unrecoverable hangs after exceeding roughly four billion submissions, leading to service outages and requiring manual intervention or reboot.

How an attack unfolds

An attacker or workload generates more than 2^32 padata submissions to padata_do_serial; the resulting seq_nr overflow misorders the list so the overflowed instance is perpetually selected next, blocking the serialization thread indefinitely.

How to fix it

Apply the upstream kernel patch that replaces the faulty comparison with unsigned integer wrap-around arithmetic; rebuild and deploy the corrected kernel image. Where distribution packages are available, upgrade to the version containing the fix.

How to confirm the fix worked

Confirm the patched kernel is running, then execute a test harness that submits more than 2^32 padata objects and verifies that serialization completes without deadlock.

Typical attack path

1. Identify a Linux kernel path that repeatedly calls padata_do_serial
2. Submit a continuous stream of padata objects until seq_nr exceeds 2^32
3. Trigger the mis-sorted reorder list entry
4. Observe the serialization worker deadlock and resulting system impact

How to detect it

Review kernel logs and application traces for repeated padata serialization stalls or hung worker threads after extended uptime; correlate with process activity that performs sustained padata submissions.

What your security team should do

• Prioritize patching on any system that uses padata for high-throughput serialization workloads
• Monitor kernel update channels for the corrected package
• Add automated regression tests that exercise padata submission counts beyond 32-bit boundaries