CVE-2024-56655

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: do not defer rule destruction via call_rcu nf_tables_chain_destroy can sleep, it can't be used from call_rcu callbacks. Moreover, nf_tables_rule_release() is only safe for error unwinding, while transaction mutex is held and the to-be-desroyed rule was not exposed to either dataplane or dumps, as it deactives+frees without the required synchronize_rcu() in-between. nft_rule_expr_deactivate() callbacks will change ->use counters of other chains/sets, see e.g. nft_lookup .deactivate callback, these must be serialized via transaction mutex. Also add a few lockdep asserts to make this more explicit. Calling synchronize_rcu() isn't ideal, but fixing this without is hard and way more intrusive. As-is, we can get: WARNING: .. net/netfilter/nf_tables_api.c:5515 nft_set_destroy+0x.. Workqueue: events nf_tables_trans_destroy_work RIP: 0010:nft_set_destroy+0x3fe/0x5c0 Call Trace: <TASK> nf_tables_trans_destroy_work+0x6b7/0xad0 process_one_work+0x64a/0xce0 worker_thread+0x613/0x10d0 In case the synchronize_rcu becomes an issue, we can explore alternatives. One way would be to allocate nft_trans_rule objects + one nft_trans_chain object, deactivate the rules + the chain and then defer the freeing to the nft destroy workqueue. We'd still need to keep the synchronize_rcu path as a fallback to handle -ENOMEM corner cases though.

Gravité et risque d'exploitation

CVE-2024-56655 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 0.22 %, ce qui la place devant 12.4 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <b8d8f53e1858178882b881b8c09f94ef0e83bf76, 6.12, 6.13, <b04df3da1b5c6f6dc7cdccc37941740c078c4043, <=6.12.*, a394c160d57f4b083bd904a22802f6fb7f5b3cea, 9eee6097ffb26cdd2adb988c0d378fa0d650c737, <6.6.67, cb401e5799e0acacb405f2128097e9c4ccf82f8a, 0, <5146c27b2780aac59876a887a5f4e793b8949862, e6c32a64d61184c2bdf89442b3d31ef530afba34, <2991dc357a28b61c13ed1f7b59e9251e2b4562fb, <=6.6.*, 6.11.8, 6.6.61, <6.12, bfd05c68e4c6320304e9f371ffa356b6e4b9cc53, 558f503f707f481bbf40efa74a938b8021df841d, c03d278fdf35e73dd0ec543b9b556876b9d9a8dc, <b0f013bebf94fe7ae75e5a53be2f2bd1cc1841e3, 6.6.67, <=*, 6.12.6, <7cf0bd232b565d9852cb25fd094f77254773e048, <27f0574253f6c24c8ee4e3f0a685b75ed3a256ed) 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/5146c27b2780aac59876a887a5f4e793b8949862
• https://git.kernel.org/stable/c/2991dc357a28b61c13ed1f7b59e9251e2b4562fb
• https://git.kernel.org/stable/c/b8d8f53e1858178882b881b8c09f94ef0e83bf76
• https://git.kernel.org/stable/c/b0f013bebf94fe7ae75e5a53be2f2bd1cc1841e3
• https://git.kernel.org/stable/c/27f0574253f6c24c8ee4e3f0a685b75ed3a256ed
• https://git.kernel.org/stable/c/7cf0bd232b565d9852cb25fd094f77254773e048
• https://git.kernel.org/stable/c/b04df3da1b5c6f6dc7cdccc37941740c078c4043