GHSA-4XH3-3533-7MMV
Vulnerability from github – Published: 2024-12-27 15:31 – Updated: 2025-06-04 15:30In 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: 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.
{
"affected": [],
"aliases": [
"CVE-2024-56655"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-12-27T15:15:25Z",
"severity": "MODERATE"
},
"details": "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.",
"id": "GHSA-4xh3-3533-7mmv",
"modified": "2025-06-04T15:30:25Z",
"published": "2024-12-27T15:31:56Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-56655"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/27f0574253f6c24c8ee4e3f0a685b75ed3a256ed"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2991dc357a28b61c13ed1f7b59e9251e2b4562fb"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5146c27b2780aac59876a887a5f4e793b8949862"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7cf0bd232b565d9852cb25fd094f77254773e048"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b04df3da1b5c6f6dc7cdccc37941740c078c4043"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b0f013bebf94fe7ae75e5a53be2f2bd1cc1841e3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b8d8f53e1858178882b881b8c09f94ef0e83bf76"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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