CVE-2024-42109

Source
https://nvd.nist.gov/vuln/detail/CVE-2024-42109
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2024-42109.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2024-42109
Downstream
Related
Published
2024-07-30T08:15:03Z
Modified
2025-08-09T20:01:27Z
Severity
  • 5.5 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
Summary
[none]
Details

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_tables: unconditionally flush pending work before notifier

syzbot reports:

KASAN: slab-uaf in nftctxupdate include/net/netfilter/nftables.h:1831 KASAN: slab-uaf in nftcommitrelease net/netfilter/nftablesapi.c:9530 KASAN: slab-uaf int nftablestransdestroywork+0x152b/0x1750 net/netfilter/nftablesapi.c:9597 Read of size 2 at addr ffff88802b0051c4 by task kworker/1:1/45 [..] Workqueue: events nftablestransdestroywork Call Trace: nftctxupdate include/net/netfilter/nftables.h:1831 [inline] nftcommitrelease net/netfilter/nftablesapi.c:9530 [inline] nftablestransdestroywork+0x152b/0x1750 net/netfilter/nftablesapi.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: nftables: do not store nftctx in transaction objects"), with this commit applied there is an unconditional fetch of table->family which is whats triggering the above splat.

References

Affected packages