GHSA-994F-F72H-4MCV
Vulnerability from github – Published: 2024-07-30 09:31 – Updated: 2025-11-04 00:31In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_tables: unconditionally flush pending work before notifier
syzbot reports:
KASAN: slab-uaf in nft_ctx_update include/net/netfilter/nf_tables.h:1831 KASAN: slab-uaf in nft_commit_release net/netfilter/nf_tables_api.c:9530 KASAN: slab-uaf int nf_tables_trans_destroy_work+0x152b/0x1750 net/netfilter/nf_tables_api.c:9597 Read of size 2 at addr ffff88802b0051c4 by task kworker/1:1/45 [..] Workqueue: events nf_tables_trans_destroy_work Call Trace: nft_ctx_update include/net/netfilter/nf_tables.h:1831 [inline] nft_commit_release net/netfilter/nf_tables_api.c:9530 [inline] nf_tables_trans_destroy_work+0x152b/0x1750 net/netfilter/nf_tables_api.c:9597
Problem is that the notifier does a conditional flush, but its possible that the table-to-be-removed is still referenced by transactions being processed by the worker, so we need to flush unconditionally.
We could make the flush_work depend on whether we found a table to delete in nf-next to avoid the flush for most cases.
AFAICS this problem is only exposed in nf-next, with commit e169285f8c56 ("netfilter: nf_tables: do not store nft_ctx in transaction objects"), with this commit applied there is an unconditional fetch of table->family which is whats triggering the above splat.
{
"affected": [],
"aliases": [
"CVE-2024-42109"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-07-30T08:15:03Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_tables: unconditionally flush pending work before notifier\n\nsyzbot reports:\n\nKASAN: slab-uaf in nft_ctx_update include/net/netfilter/nf_tables.h:1831\nKASAN: slab-uaf in nft_commit_release net/netfilter/nf_tables_api.c:9530\nKASAN: slab-uaf int nf_tables_trans_destroy_work+0x152b/0x1750 net/netfilter/nf_tables_api.c:9597\nRead of size 2 at addr ffff88802b0051c4 by task kworker/1:1/45\n[..]\nWorkqueue: events nf_tables_trans_destroy_work\nCall Trace:\n nft_ctx_update include/net/netfilter/nf_tables.h:1831 [inline]\n nft_commit_release net/netfilter/nf_tables_api.c:9530 [inline]\n nf_tables_trans_destroy_work+0x152b/0x1750 net/netfilter/nf_tables_api.c:9597\n\nProblem is that the notifier does a conditional flush, but its possible\nthat the table-to-be-removed is still referenced by transactions being\nprocessed by the worker, so we need to flush unconditionally.\n\nWe could make the flush_work depend on whether we found a table to delete\nin nf-next to avoid the flush for most cases.\n\nAFAICS this problem is only exposed in nf-next, with\ncommit e169285f8c56 (\"netfilter: nf_tables: do not store nft_ctx in transaction objects\"),\nwith this commit applied there is an unconditional fetch of\ntable-\u003efamily which is whats triggering the above splat.",
"id": "GHSA-994f-f72h-4mcv",
"modified": "2025-11-04T00:31:05Z",
"published": "2024-07-30T09:31:51Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-42109"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/09e650c3a3a7d804430260510534ccbf71c75b2e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3325628cb36b7f216c5716e7b5124d9dc81199e4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4c06c13317b9a08decedcd7aaf706691e336277c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/55a40406aac555defe9bdd0adec9508116ce7cb1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9f6958ba2e902f9820c594869bd710ba74b7c4c0"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html"
}
],
"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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