{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2024-56655","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2024-12-27T15:00:39.841Z","datePublished":"2024-12-27T15:06:19.033Z","dateUpdated":"2026-08-05T11:45:53.066Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T11:45:53.066Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_tables: do not defer rule destruction via call_rcu\n\nnf_tables_chain_destroy can sleep, it can't be used from call_rcu\ncallbacks.\n\nMoreover, nf_tables_rule_release() is only safe for error unwinding,\nwhile transaction mutex is held and the to-be-desroyed rule was not\nexposed to either dataplane or dumps, as it deactives+frees without\nthe required synchronize_rcu() in-between.\n\nnft_rule_expr_deactivate() callbacks will change ->use counters\nof other chains/sets, see e.g. nft_lookup .deactivate callback, these\nmust be serialized via transaction mutex.\n\nAlso add a few lockdep asserts to make this more explicit.\n\nCalling synchronize_rcu() isn't ideal, but fixing this without is hard\nand way more intrusive.  As-is, we can get:\n\nWARNING: .. net/netfilter/nf_tables_api.c:5515 nft_set_destroy+0x..\nWorkqueue: events nf_tables_trans_destroy_work\nRIP: 0010:nft_set_destroy+0x3fe/0x5c0\nCall Trace:\n <TASK>\n nf_tables_trans_destroy_work+0x6b7/0xad0\n process_one_work+0x64a/0xce0\n worker_thread+0x613/0x10d0\n\nIn case the synchronize_rcu becomes an issue, we can explore alternatives.\n\nOne way would be to allocate nft_trans_rule objects + one nft_trans_chain\nobject, deactivate the rules + the chain and then defer the freeing to the\nnft destroy workqueue.  We'd still need to keep the synchronize_rcu path as\na fallback to handle -ENOMEM corner cases though."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerable path is driven entirely from local interfaces — nfnetlink/NETLINK_NETFILTER to build a netdev-family basechain with rules, and RTNETLINK to unregister the device that fires the NETDEV_UNREGISTER notifier. No remote peer can drive basechain release.\nAC:L - The attacker owns both sides: it creates the netns, the device, and the ruleset, chooses when to delete the device, and issues concurrent nftables transactions that race the unserialized softirq callback, repeating indefinitely; the sleeping-in-atomic path (`cancel_delayed_work_sync`/`mutex_lock` from an RCU softirq callback) is deterministic and needs no race at all.\nPR:L - nfnetlink only requires `netlink_net_capable(skb, CAP_NET_ADMIN)`, evaluated against the network namespace's user_ns, so an unprivileged local user obtains everything needed via `unshare -Urn` — including creating and deleting the dummy/veth device that triggers the notifier.\nUI:N - The attacker performs every step itself — ruleset setup, device removal, and the concurrent transactions; no victim action or pre-existing administrator configuration is needed.\nS:U - Corruption is confined to nf_tables kernel objects within the same kernel security authority; there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - Unserialized `nft_use_dec()` on `set->use`/`chain->use`/`obj->use` races the commit-mutex-protected control plane, so counters underflow and still-referenced sets/chains are freed, yielding a use-after-free whose reclaimed contents the attacker can shape and read back via ruleset dumps.\nI:H - The softirq callback performs `list_del_rcu()` on `table->sets`/`table->chains` and `rhltable_remove()` on `chains_ht` concurrently with control-plane insertions/removals, giving list and rhashtable corruption on top of the UAF — both standard springboards to controlled kernel writes and control-flow hijack.\nA:H - Sleeping functions (`cancel_delayed_work_sync`, `mutex_lock` via `nf_ct_netns_put`, `nf_tables_chain_destroy`) invoked from an RCU softirq callback produce \"sleeping function called from invalid context\" BUGs and scheduler corruption, and the refcount/list corruption reliably ends in WARNs, oopses, and panics."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/netfilter/nf_tables.h","net/netfilter/nf_tables_api.c"],"versions":[{"version":"9eee6097ffb26cdd2adb988c0d378fa0d650c737","lessThan":"5146c27b2780aac59876a887a5f4e793b8949862","status":"affected","versionType":"git"},{"version":"558f503f707f481bbf40efa74a938b8021df841d","lessThan":"2991dc357a28b61c13ed1f7b59e9251e2b4562fb","status":"affected","versionType":"git"},{"version":"a394c160d57f4b083bd904a22802f6fb7f5b3cea","lessThan":"b8d8f53e1858178882b881b8c09f94ef0e83bf76","status":"affected","versionType":"git"},{"version":"e6c32a64d61184c2bdf89442b3d31ef530afba34","lessThan":"b0f013bebf94fe7ae75e5a53be2f2bd1cc1841e3","status":"affected","versionType":"git"},{"version":"bfd05c68e4c6320304e9f371ffa356b6e4b9cc53","lessThan":"27f0574253f6c24c8ee4e3f0a685b75ed3a256ed","status":"affected","versionType":"git"},{"version":"c03d278fdf35e73dd0ec543b9b556876b9d9a8dc","lessThan":"7cf0bd232b565d9852cb25fd094f77254773e048","status":"affected","versionType":"git"},{"version":"c03d278fdf35e73dd0ec543b9b556876b9d9a8dc","lessThan":"b04df3da1b5c6f6dc7cdccc37941740c078c4043","status":"affected","versionType":"git"},{"version":"cb401e5799e0acacb405f2128097e9c4ccf82f8a","status":"affected","versionType":"git"},{"version":"6.6.61","lessThan":"6.6.67","status":"affected","versionType":"semver"},{"version":"6.11.8","lessThan":"6.12","status":"affected","versionType":"semver"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/netfilter/nf_tables.h","net/netfilter/nf_tables_api.c"],"versions":[{"version":"6.12","status":"affected"},{"version":"0","lessThan":"6.12","status":"unaffected","versionType":"semver"},{"version":"6.6.67","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.6","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.13","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6.61","versionEndExcluding":"6.6.67"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"6.12.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"6.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11.8"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/5146c27b2780aac59876a887a5f4e793b8949862"},{"url":"https://git.kernel.org/stable/c/2991dc357a28b61c13ed1f7b59e9251e2b4562fb"},{"url":"https://git.kernel.org/stable/c/b8d8f53e1858178882b881b8c09f94ef0e83bf76"},{"url":"https://git.kernel.org/stable/c/b0f013bebf94fe7ae75e5a53be2f2bd1cc1841e3"},{"url":"https://git.kernel.org/stable/c/27f0574253f6c24c8ee4e3f0a685b75ed3a256ed"},{"url":"https://git.kernel.org/stable/c/7cf0bd232b565d9852cb25fd094f77254773e048"},{"url":"https://git.kernel.org/stable/c/b04df3da1b5c6f6dc7cdccc37941740c078c4043"}],"title":"netfilter: nf_tables: do not defer rule destruction via call_rcu","x_generator":{"engine":"bippy-1.2.0"}}}}