linux-cve-announce - CVE-2024-56641: net/smc: initialize close

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Message-ID: <2024122736-CVE-2024-56641-5492@gregkh>
Date: Fri, 27 Dec 2024 16:02:42 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-56641: net/smc: initialize close_work early to avoid warning

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

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

net/smc: initialize close_work early to avoid warning

We encountered a warning that close_work was canceled before
initialization.

  WARNING: CPU: 7 PID: 111103 at kernel/workqueue.c:3047 __flush_work+0x19e/0x1b0
  Workqueue: events smc_lgr_terminate_work [smc]
  RIP: 0010:__flush_work+0x19e/0x1b0
  Call Trace:
   ? __wake_up_common+0x7a/0x190
   ? work_busy+0x80/0x80
   __cancel_work_timer+0xe3/0x160
   smc_close_cancel_work+0x1a/0x70 [smc]
   smc_close_active_abort+0x207/0x360 [smc]
   __smc_lgr_terminate.part.38+0xc8/0x180 [smc]
   process_one_work+0x19e/0x340
   worker_thread+0x30/0x370
   ? process_one_work+0x340/0x340
   kthread+0x117/0x130
   ? __kthread_cancel_work+0x50/0x50
   ret_from_fork+0x22/0x30

This is because when smc_close_cancel_work is triggered, e.g. the RDMA
driver is rmmod and the LGR is terminated, the conn->close_work is
flushed before initialization, resulting in WARN_ON(!work->func).

__smc_lgr_terminate             | smc_connect_{rdma|ism}
-------------------------------------------------------------
                                | smc_conn_create
				| \- smc_lgr_register_conn
for conn in lgr->conns_all      |
\- smc_conn_kill                |
   \- smc_close_active_abort    |
      \- smc_close_cancel_work  |
         \- cancel_work_sync    |
            \- __flush_work     |
	         (close_work)   |
	                        | smc_close_init
	                        | \- INIT_WORK(&close_work)

So fix this by initializing close_work before establishing the
connection.

The Linux kernel CVE team has assigned CVE-2024-56641 to this issue.

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

	Issue introduced in 4.12 with commit 46c28dbd4c23c3f7fa37f5ea48772af79c9cc40e and fixed in 6.6.66 with commit f0c37002210aaede10dae849d1a78efc2243add2
	Issue introduced in 4.12 with commit 46c28dbd4c23c3f7fa37f5ea48772af79c9cc40e and fixed in 6.12.5 with commit 6638e52dcfafaf1b9cbc34544f0c832db0069ea1
	Issue introduced in 4.12 with commit 46c28dbd4c23c3f7fa37f5ea48772af79c9cc40e and fixed in 6.13-rc2 with commit 0541db8ee32c09463a72d0987382b3a3336b0043

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-2024-56641
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/f0c37002210aaede10dae849d1a78efc2243add2
	https://git.kernel.org/stable/c/6638e52dcfafaf1b9cbc34544f0c832db0069ea1
	https://git.kernel.org/stable/c/0541db8ee32c09463a72d0987382b3a3336b0043