Bug 2301472 (CVE-2024-42109) - CVE-2024-42109 kernel: netfilter: nf_tables: unconditionally flush pending work before notifier
Summary: CVE-2024-42109 kernel: netfilter: nf_tables: unconditionally flush pending wo...
Keywords:
Status: NEW
Alias: CVE-2024-42109
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On: 2301771
Blocks:
TreeView+ depends on / blocked
 
Reported: 2024-07-30 08:30 UTC by OSIDB Bzimport
Modified: 2024-09-23 08:44 UTC (History)
4 users (show)

Fixed In Version: kernel 5.15.163, kernel 6.1.98, kernel 6.6.39, kernel 6.9.9, kernel 6.10
Clone Of:
Environment:
Last Closed:
Embargoed:


Attachments (Terms of Use)

Description OSIDB Bzimport 2024-07-30 08:30:29 UTC
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.

Comment 1 Mauro Matteo Cascella 2024-07-30 18:43:28 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024073021-CVE-2024-42109-2531@gregkh/T

Comment 2 Mauro Matteo Cascella 2024-07-30 18:43:50 UTC
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 2301771]


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