CVE-2024-56655 (GCVE-0-2024-56655)
Vulnerability from cvelistv5
Published
2024-12-27 15:06
Modified
2026-08-05 11:45
Severity ?
VLAI Severity ?
EPSS score ?
Summary
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.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 9eee6097ffb26cdd2adb988c0d378fa0d650c737 Version: 558f503f707f481bbf40efa74a938b8021df841d Version: a394c160d57f4b083bd904a22802f6fb7f5b3cea Version: e6c32a64d61184c2bdf89442b3d31ef530afba34 Version: bfd05c68e4c6320304e9f371ffa356b6e4b9cc53 Version: c03d278fdf35e73dd0ec543b9b556876b9d9a8dc Version: c03d278fdf35e73dd0ec543b9b556876b9d9a8dc Version: cb401e5799e0acacb405f2128097e9c4ccf82f8a Version: 6.6.61 ≤ Version: 6.11.8 ≤ |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"include/net/netfilter/nf_tables.h",
"net/netfilter/nf_tables_api.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "5146c27b2780aac59876a887a5f4e793b8949862",
"status": "affected",
"version": "9eee6097ffb26cdd2adb988c0d378fa0d650c737",
"versionType": "git"
},
{
"lessThan": "2991dc357a28b61c13ed1f7b59e9251e2b4562fb",
"status": "affected",
"version": "558f503f707f481bbf40efa74a938b8021df841d",
"versionType": "git"
},
{
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"status": "affected",
"version": "a394c160d57f4b083bd904a22802f6fb7f5b3cea",
"versionType": "git"
},
{
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"status": "affected",
"version": "e6c32a64d61184c2bdf89442b3d31ef530afba34",
"versionType": "git"
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{
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"status": "affected",
"version": "bfd05c68e4c6320304e9f371ffa356b6e4b9cc53",
"versionType": "git"
},
{
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},
{
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"version": "cb401e5799e0acacb405f2128097e9c4ccf82f8a",
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},
{
"lessThan": "6.6.67",
"status": "affected",
"version": "6.6.61",
"versionType": "semver"
},
{
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"status": "affected",
"version": "6.11.8",
"versionType": "semver"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"include/net/netfilter/nf_tables.h",
"net/netfilter/nf_tables_api.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.12"
},
{
"lessThan": "6.12",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.67",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.6",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "6.13",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.67",
"versionStartIncluding": "6.6.61",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.6",
"versionStartIncluding": "6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.11.8",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"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\u0027t 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 -\u003euse 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\u0027t 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 \u003cTASK\u003e\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\u0027d still need to keep the synchronize_rcu path as\na fallback to handle -ENOMEM corner cases though."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The vulnerable path is driven entirely from local interfaces \u2014 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\u0027s user_ns, so an unprivileged local user obtains everything needed via `unshare -Urn` \u2014 including creating and deleting the dummy/veth device that triggers the notifier.\nUI:N - The attacker performs every step itself \u2014 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-\u003euse`/`chain-\u003euse`/`obj-\u003euse` 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-\u003esets`/`table-\u003echains` and `rhltable_remove()` on `chains_ht` concurrently with control-plane insertions/removals, giving list and rhashtable corruption on top of the UAF \u2014 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."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-05T11:45:53.066Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"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"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2024-56655",
"datePublished": "2024-12-27T15:06:19.033Z",
"dateReserved": "2024-12-27T15:00:39.841Z",
"dateUpdated": "2026-08-05T11:45:53.066Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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