{ "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 \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" } } } }