CVE-2024-50285

What it actually does

Unbounded allocation of ksmbd_work_cache entries when a client issues many simultaneous SMB requests, bypassing the existing credit mechanism and leading to memory exhaustion and OOM.

Why it matters to the business

Denial of service that can crash or destabilize Linux systems running ksmbd, interrupting file-sharing services and requiring manual intervention or reboot.

How an attack unfolds

An attacker establishes an SMB session to a vulnerable ksmbd server and issues a large number of concurrent operations that each consume at least one credit; once the implicit maximum is exceeded the kernel continues allocating work items until memory is exhausted.

How to fix it

Apply the upstream patch that adds an explicit check against max credits before allocating new ksmbd_work items; rebuild and deploy the fixed kernel. Where distribution packages are available, upgrade to the corrected kernel version that contains commit resolving CVE-2024-50285.

How to confirm the fix worked

Confirm the running kernel contains the credit-limit check in ksmbd; attempt to reproduce the simultaneous-request scenario in a test environment and verify that allocations are now bounded and OOM does not occur.

Typical attack path

1. Establish authenticated or guest SMB connection to target ksmbd instance
2. Send a burst of simultaneous SMB requests designed to consume credits
3. Continue flooding until ksmbd_work_cache allocations trigger OOM killer or system hang
4. Observe service interruption or kernel panic confirming successful DoS

How to detect it

Review kernel logs for repeated ksmbd work-item allocations followed by OOM killer activity; correlate with SMB connection logs showing high concurrency from single clients.

What your security team should do

• Prioritize kernel updates on all systems exposing ksmbd/SMB shares
• Monitor EPSS and KEV status for any future elevation in exploitability
• Restrict SMB access to trusted networks and enforce strong authentication to reduce attack surface