linux-cve-announce - CVE-2024-56640: net/smc: fix LGR and link use-after-free issue

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <2024122736-CVE-2024-56640-ef22@gregkh>
Date: Fri, 27 Dec 2024 16:02:41 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-56640: net/smc: fix LGR and link use-after-free issue

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

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

net/smc: fix LGR and link use-after-free issue

We encountered a LGR/link use-after-free issue, which manifested as
the LGR/link refcnt reaching 0 early and entering the clear process,
making resource access unsafe.

 refcount_t: addition on 0; use-after-free.
 WARNING: CPU: 14 PID: 107447 at lib/refcount.c:25 refcount_warn_saturate+0x9c/0x140
 Workqueue: events smc_lgr_terminate_work [smc]
 Call trace:
  refcount_warn_saturate+0x9c/0x140
  __smc_lgr_terminate.part.45+0x2a8/0x370 [smc]
  smc_lgr_terminate_work+0x28/0x30 [smc]
  process_one_work+0x1b8/0x420
  worker_thread+0x158/0x510
  kthread+0x114/0x118

or

 refcount_t: underflow; use-after-free.
 WARNING: CPU: 6 PID: 93140 at lib/refcount.c:28 refcount_warn_saturate+0xf0/0x140
 Workqueue: smc_hs_wq smc_listen_work [smc]
 Call trace:
  refcount_warn_saturate+0xf0/0x140
  smcr_link_put+0x1cc/0x1d8 [smc]
  smc_conn_free+0x110/0x1b0 [smc]
  smc_conn_abort+0x50/0x60 [smc]
  smc_listen_find_device+0x75c/0x790 [smc]
  smc_listen_work+0x368/0x8a0 [smc]
  process_one_work+0x1b8/0x420
  worker_thread+0x158/0x510
  kthread+0x114/0x118

It is caused by repeated release of LGR/link refcnt. One suspect is that
smc_conn_free() is called repeatedly because some smc_conn_free() from
server listening path are not protected by sock lock.

e.g.

Calls under socklock        | smc_listen_work
-------------------------------------------------------
lock_sock(sk)               | smc_conn_abort
smc_conn_free               | \- smc_conn_free
\- smcr_link_put            |    \- smcr_link_put (duplicated)
release_sock(sk)

So here add sock lock protection in smc_listen_work() path, making it
exclusive with other connection operations.

The Linux kernel CVE team has assigned CVE-2024-56640 to this issue.

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

	Issue introduced in 4.18 with commit 3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 and fixed in 5.15.174 with commit f502a88fdd415647a1f2dc45fac71b9c522a052b
	Issue introduced in 4.18 with commit 3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 and fixed in 6.1.120 with commit 0cf598548a6c36d90681d53c6b77d52363f2f295
	Issue introduced in 4.18 with commit 3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 and fixed in 6.6.66 with commit 673d606683ac70bc074ca6676b938bff18635226
	Issue introduced in 4.18 with commit 3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 and fixed in 6.12.5 with commit 6f0ae06a234a78ae137064f2c89135ac078a00eb
	Issue introduced in 4.18 with commit 3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 and fixed in 6.13-rc2 with commit 2c7f14ed9c19ec0f149479d1c2842ec1f9bf76d7

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-2024-56640
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/smc/af_smc.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/f502a88fdd415647a1f2dc45fac71b9c522a052b
	https://git.kernel.org/stable/c/0cf598548a6c36d90681d53c6b77d52363f2f295
	https://git.kernel.org/stable/c/673d606683ac70bc074ca6676b938bff18635226
	https://git.kernel.org/stable/c/6f0ae06a234a78ae137064f2c89135ac078a00eb
	https://git.kernel.org/stable/c/2c7f14ed9c19ec0f149479d1c2842ec1f9bf76d7