CVE-2024-35808

What it actually does

Unsafe direct call to md_reap_sync_thread() from raid_message() without reconfig_mutex allows concurrent modification of mutex-protected fields; acquiring the mutex instead introduces deadlock with idle/frozen sync thread paths.

Why it matters to the business

Systems using Linux software RAID (dm-raid) may experience kernel instability, crashes, or data corruption during sync operations, affecting storage reliability and uptime in servers and appliances.

How an attack unfolds

An attacker with local access triggers concurrent raid_message and sync thread operations to race on unprotected fields, potentially causing use-after-free, memory corruption, or deadlock in the md layer.

How to fix it

Update the Linux kernel to a version containing commit 347dcdc15a1706f61aa545ae498ededdf31aeebc or later; rebuild and reboot affected systems. Where immediate patching is impossible, avoid manual RAID reconfiguration during active sync operations.

How to confirm the fix worked

Confirm the running kernel contains commit 347dcdc15a1706f61aa545ae498ededdf31aeebc via 'uname -r' and kernel source; inspect dm-raid code for use of stop_sync_thread() instead of direct md_reap_sync_thread() calls.

Typical attack path

1. Obtain local unprivileged access on a Linux system using dm-raid
2. Issue concurrent RAID array messages while a sync thread is active
3. Trigger the unsafe md_reap_sync_thread path without mutex protection
4. Exploit resulting race to corrupt kernel structures or induce panic

How to detect it

Review kernel logs for md/raid related oops, warnings about reconfig_mutex, or sync thread state inconsistencies around the time of any storage configuration changes; no public exploitation artifacts are known.

What your security team should do

• Prioritize kernel upgrade on all systems exposing dm-raid devices within the next maintenance window
• Monitor vendor advisories for backported fixes in distribution kernels
• Test RAID array behavior under load after patching to verify stability