CVE-2026-43042

Summary

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

mpls: add seqcount to protect the platform_label{,s} pair

The RCU-protected codepaths (mpls_forward, mpls_dump_routes) can have an inconsistent view of platform_labels vs platform_label in case of a concurrent resize (resize_platform_label_table, under platform_mutex). This can lead to OOB accesses.

This patch adds a seqcount, so that we get a consistent snapshot.

Note that mpls_label_ok is also susceptible to this, so the check against RTA_DST in rtm_to_route_config, done outside platform_mutex, is not sufficient. This value gets passed to mpls_label_ok once more in both mpls_route_add and mpls_route_del, so there is no issue, but that additional check must not be removed.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/5bb3caf0bbfb56f1a00d2af072ac3d8395a3b9ef
• https://git.kernel.org/stable/c/629ec78ef8608d955ce217880cdc3e1873af3a15

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