CVE-2024-47678

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

icmp: change the order of rate limits

ICMP messages are ratelimited :

After the blamed commits, the two rate limiters are applied in this order:

1) host wide ratelimit (icmp_global_allow())

2) Per destination ratelimit (inetpeer based)

In order to avoid side-channels attacks, we need to apply

the per destination check first.

This patch makes the following change :

1) icmp_global_allow() checks if the host wide limit is reached.

But credits are not yet consumed. This is deferred to 3)

2) The per destination limit is checked/updated.

This might add a new node in inetpeer tree.

3) icmp_global_consume() consumes tokens if prior operations succeeded.

This means that host wide ratelimit is still effective

in keeping inetpeer tree small even under DDOS.

As a bonus, I removed icmp_global.lock as the fast path

can use a lock-free operation.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References