CVE-2024-42109 Affecting kernel-syms-azure package, versions <6.4.0-150600.8.11.1


Severity

Recommended
0.0
medium
0
10

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.04% (6th percentile)

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  • Snyk IDSNYK-SLES156-KERNELSYMSAZURE-7929681
  • published11 Sept 2024
  • disclosed10 Sept 2024

Introduced: 10 Sep 2024

CVE-2024-42109  (opens in a new tab)

How to fix?

Upgrade SLES:15.6 kernel-syms-azure to version 6.4.0-150600.8.11.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-syms-azure package and not the kernel-syms-azure package as distributed by SLES. See How to fix? for SLES:15.6 relevant fixed versions and status.

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 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.

CVSS Scores

version 3.1