CVE-2024-56703

/// Technical description

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

ipv6: Fix soft lockups in fib6_select_path under high next hop churn

Soft lockups have been observed on a cluster of Linux-based edge routers

located in a highly dynamic environment. Using the `bird` service, these

routers continuously update BGP-advertised routes due to frequently

changing nexthop destinations, while also managing significant IPv6

traffic. The lockups occur during the traversal of the multipath

circular linked-list in the `fib6_select_path` function, particularly

while iterating through the siblings in the list. The issue typically

arises when the nodes of the linked list are unexpectedly deleted

concurrently on a different core—indicated by their 'next' and

'previous' elements pointing back to the node itself and their reference

count dropping to zero. This results in an infinite loop, leading to a

soft lockup that triggers a system panic via the watchdog timer.

Apply RCU primitives in the problem

/// 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