CVE-2025-40215

Description

In the Linux kernel, the following vulnerability has been resolved: xfrm: delete x->tunnel as we delete x The ipcomp fallback tunnels currently get deleted (from the various lists and hashtables) as the last user state that needed that fallback is destroyed (not deleted). If a reference to that user state still exists, the fallback state will remain on the hashtables/lists, triggering the WARN in xfrm_state_fini. Because of those remaining references, the fix in commit f75a2804da39 ("xfrm: destroy xfrm_state synchronously on net exit path") is not complete. We recently fixed one such situation in TCP due to defered freeing of skbs (commit 9b6412e6979f ("tcp: drop secpath at the same time as we currently drop dst")). This can also happen due to IP reassembly: skbs with a secpath remain on the reassembly queue until netns destruction. If we can't guarantee that the queues are flushed by the time xfrm_state_fini runs, there may still be references to a (user) xfrm_state, preventing the timely deletion of the corresponding fallback state. Instead of chasing each instance of skbs holding a secpath one by one, this patch fixes the issue directly within xfrm, by deleting the fallback state as soon as the last user state depending on it has been deleted. Destruction will still happen when the final reference is dropped. A separate lockdep class for the fallback state is required since we're going to lock x->tunnel while x is locked.

Gravité et risque d'exploitation

CVE-2025-40215 obtient un score CVSS de 7.8/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.14 %, ce qui la place devant 3.3 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.1.*, <2.6.29, <0da961fa46da1b37ef868d9b603bd202136f8f8e, <=6.12.*, 6.1.160, 0, <d0e0d1097118461463b76562c7ebaabaa5b90b13, 6.6.120, 2.6.29, 5.15.198, <=5.10.*, <=6.6.*, 6.16, <dc3636912d41770466543623cb76e7b88fdb42c7, 6.12.62, 5.10.248, <b441cf3f8c4b8576639d20c8eb4aa32917602ecd, <=*, <=5.15.*, <1b28a7fae0128fa140a7dccd995182ff6cd1c67b, <4b2c17d0f9be8b58bb30468bc81a4b61c985b04e, 9d4139c76905833afcb77fe8ccc17f302a0eb9ab) est présent sur votre parc.
• Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
• À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
• Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

• https://git.kernel.org/stable/c/1b28a7fae0128fa140a7dccd995182ff6cd1c67b
• https://git.kernel.org/stable/c/4b2c17d0f9be8b58bb30468bc81a4b61c985b04e
• https://git.kernel.org/stable/c/0da961fa46da1b37ef868d9b603bd202136f8f8e
• https://git.kernel.org/stable/c/d0e0d1097118461463b76562c7ebaabaa5b90b13
• https://git.kernel.org/stable/c/dc3636912d41770466543623cb76e7b88fdb42c7
• https://git.kernel.org/stable/c/b441cf3f8c4b8576639d20c8eb4aa32917602ecd