linux-cve-announce - CVE-2022-49698: netfilter: use get_random

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Message-ID: <2025022628-CVE-2022-49698-9ddd@gregkh>
Date: Wed, 26 Feb 2025 03:24:21 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2022-49698: netfilter: use get_random_u32 instead of prandom

Description
===========

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

netfilter: use get_random_u32 instead of prandom

bh might occur while updating per-cpu rnd_state from user context,
ie. local_out path.

BUG: using smp_processor_id() in preemptible [00000000] code: nginx/2725
caller is nft_ng_random_eval+0x24/0x54 [nft_numgen]
Call Trace:
 check_preemption_disabled+0xde/0xe0
 nft_ng_random_eval+0x24/0x54 [nft_numgen]

Use the random driver instead, this also avoids need for local prandom
state. Moreover, prandom now uses the random driver since d4150779e60f
("random32: use real rng for non-deterministic randomness").

Based on earlier patch from Pablo Neira.

The Linux kernel CVE team has assigned CVE-2022-49698 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 4.18 with commit 978d8f9055c3a7c35db2ac99cd2580b993396e33 and fixed in 5.10.127 with commit 15cc30ac2a8d7185f8ebf97dd1ddd90a7c79783b
	Issue introduced in 4.18 with commit 978d8f9055c3a7c35db2ac99cd2580b993396e33 and fixed in 5.15.51 with commit d0906b0fffc9f19bc42708ca3e84e2089088386c
	Issue introduced in 4.18 with commit 978d8f9055c3a7c35db2ac99cd2580b993396e33 and fixed in 5.18.8 with commit 6ce71f83f798be7e1ca68707fec449fbecb38852
	Issue introduced in 4.18 with commit 978d8f9055c3a7c35db2ac99cd2580b993396e33 and fixed in 5.19 with commit b1fd94e704571f98b21027340eecf821b2bdffba

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2022-49698
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	net/netfilter/nft_meta.c
	net/netfilter/nft_numgen.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/15cc30ac2a8d7185f8ebf97dd1ddd90a7c79783b
	https://git.kernel.org/stable/c/d0906b0fffc9f19bc42708ca3e84e2089088386c
	https://git.kernel.org/stable/c/6ce71f83f798be7e1ca68707fec449fbecb38852
	https://git.kernel.org/stable/c/b1fd94e704571f98b21027340eecf821b2bdffba