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Message-ID: <2025091515-CVE-2023-53233-8c6b@gregkh>
Date: Mon, 15 Sep 2025 16:22:07 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53233: net/smc: fix deadlock triggered by cancel_delayed_work_syn()

From: Greg Kroah-Hartman <gregkh@...nel.org>

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

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

net/smc: fix deadlock triggered by cancel_delayed_work_syn()

The following LOCKDEP was detected:
		Workqueue: events smc_lgr_free_work [smc]
		WARNING: possible circular locking dependency detected
		6.1.0-20221027.rc2.git8.56bc5b569087.300.fc36.s390x+debug #1 Not tainted
		------------------------------------------------------
		kworker/3:0/176251 is trying to acquire lock:
		00000000f1467148 ((wq_completion)smc_tx_wq-00000000#2){+.+.}-{0:0},
			at: __flush_workqueue+0x7a/0x4f0
		but task is already holding lock:
		0000037fffe97dc8 ((work_completion)(&(&lgr->free_work)->work)){+.+.}-{0:0},
			at: process_one_work+0x232/0x730
		which lock already depends on the new lock.
		the existing dependency chain (in reverse order) is:
		-> #4 ((work_completion)(&(&lgr->free_work)->work)){+.+.}-{0:0}:
		       __lock_acquire+0x58e/0xbd8
		       lock_acquire.part.0+0xe2/0x248
		       lock_acquire+0xac/0x1c8
		       __flush_work+0x76/0xf0
		       __cancel_work_timer+0x170/0x220
		       __smc_lgr_terminate.part.0+0x34/0x1c0 [smc]
		       smc_connect_rdma+0x15e/0x418 [smc]
		       __smc_connect+0x234/0x480 [smc]
		       smc_connect+0x1d6/0x230 [smc]
		       __sys_connect+0x90/0xc0
		       __do_sys_socketcall+0x186/0x370
		       __do_syscall+0x1da/0x208
		       system_call+0x82/0xb0
		-> #3 (smc_client_lgr_pending){+.+.}-{3:3}:
		       __lock_acquire+0x58e/0xbd8
		       lock_acquire.part.0+0xe2/0x248
		       lock_acquire+0xac/0x1c8
		       __mutex_lock+0x96/0x8e8
		       mutex_lock_nested+0x32/0x40
		       smc_connect_rdma+0xa4/0x418 [smc]
		       __smc_connect+0x234/0x480 [smc]
		       smc_connect+0x1d6/0x230 [smc]
		       __sys_connect+0x90/0xc0
		       __do_sys_socketcall+0x186/0x370
		       __do_syscall+0x1da/0x208
		       system_call+0x82/0xb0
		-> #2 (sk_lock-AF_SMC){+.+.}-{0:0}:
		       __lock_acquire+0x58e/0xbd8
		       lock_acquire.part.0+0xe2/0x248
		       lock_acquire+0xac/0x1c8
		       lock_sock_nested+0x46/0xa8
		       smc_tx_work+0x34/0x50 [smc]
		       process_one_work+0x30c/0x730
		       worker_thread+0x62/0x420
		       kthread+0x138/0x150
		       __ret_from_fork+0x3c/0x58
		       ret_from_fork+0xa/0x40
		-> #1 ((work_completion)(&(&smc->conn.tx_work)->work)){+.+.}-{0:0}:
		       __lock_acquire+0x58e/0xbd8
		       lock_acquire.part.0+0xe2/0x248
		       lock_acquire+0xac/0x1c8
		       process_one_work+0x2bc/0x730
		       worker_thread+0x62/0x420
		       kthread+0x138/0x150
		       __ret_from_fork+0x3c/0x58
		       ret_from_fork+0xa/0x40
		-> #0 ((wq_completion)smc_tx_wq-00000000#2){+.+.}-{0:0}:
		       check_prev_add+0xd8/0xe88
		       validate_chain+0x70c/0xb20
		       __lock_acquire+0x58e/0xbd8
		       lock_acquire.part.0+0xe2/0x248
		       lock_acquire+0xac/0x1c8
		       __flush_workqueue+0xaa/0x4f0
		       drain_workqueue+0xaa/0x158
		       destroy_workqueue+0x44/0x2d8
		       smc_lgr_free+0x9e/0xf8 [smc]
		       process_one_work+0x30c/0x730
		       worker_thread+0x62/0x420
		       kthread+0x138/0x150
		       __ret_from_fork+0x3c/0x58
		       ret_from_fork+0xa/0x40
		other info that might help us debug this:
		Chain exists of:
		  (wq_completion)smc_tx_wq-00000000#2
	  	  --> smc_client_lgr_pending
		  --> (work_completion)(&(&lgr->free_work)->work)
		 Possible unsafe locking scenario:
		       CPU0                    CPU1
		       ----                    ----
		  lock((work_completion)(&(&lgr->free_work)->work));
		                   lock(smc_client_lgr_pending);
		                   lock((work_completion)
					(&(&lgr->free_work)->work));
		  lock((wq_completion)smc_tx_wq-00000000#2);
		 *** DEADLOCK ***
		2 locks held by kworker/3:0/176251:
		 #0: 0000000080183548
			((wq_completion)events){+.+.}-{0:0},
				at: process_one_work+0x232/0x730
		 #1: 0000037fffe97dc8
			((work_completion)
			 (&(&lgr->free_work)->work)){+.+.}-{0:0},
				at: process_one_work+0x232/0x730
		stack backtrace:
		CPU: 3 PID: 176251 Comm: kworker/3:0 Not tainted
		Hardware name: IBM 8561 T01 701 (z/VM 7.2.0)
		Call Trace:
		 [<000000002983c3e4>] dump_stack_lvl+0xac/0x100
		 [<0000000028b477ae>] check_noncircular+0x13e/0x160
		 [<0000000028b48808>] check_prev_add+0xd8/0xe88
		 [<0000000028b49cc4>] validate_chain+0x70c/0xb20
		 [<0000000028b4bd26>] __lock_acquire+0x58e/0xbd8
		 [<0000000028b4cf6a>] lock_acquire.part.0+0xe2/0x248
		 [<0000000028b4d17c>] lock_acquire+0xac/0x1c8
		 [<0000000028addaaa>] __flush_workqueue+0xaa/0x4f0
		 [<0000000028addf9a>] drain_workqueue+0xaa/0x158
		 [<0000000028ae303c>] destroy_workqueue+0x44/0x2d8
		 [<000003ff8029af26>] smc_lgr_free+0x9e/0xf8 [smc]
		 [<0000000028adf3d4>] process_one_work+0x30c/0x730
		 [<0000000028adf85a>] worker_thread+0x62/0x420
		 [<0000000028aeac50>] kthread+0x138/0x150
		 [<0000000028a63914>] __ret_from_fork+0x3c/0x58
		 [<00000000298503da>] ret_from_fork+0xa/0x40
		INFO: lockdep is turned off.
===================================================================

This deadlock occurs because cancel_delayed_work_sync() waits for
the work(&lgr->free_work) to finish, while the &lgr->free_work
waits for the work(lgr->tx_wq), which needs the sk_lock-AF_SMC, that
is already used under the mutex_lock.

The solution is to use cancel_delayed_work() instead, which kills
off a pending work.

The Linux kernel CVE team has assigned CVE-2023-53233 to this issue.


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

	Issue introduced in 5.8 with commit a52bcc919b14c9d78f03b2b4ff604e5ca69c7e6d and fixed in 5.10.176 with commit 9708efad9ba5095b9bb7916e11a135b3bd66c071
	Issue introduced in 5.8 with commit a52bcc919b14c9d78f03b2b4ff604e5ca69c7e6d and fixed in 5.15.104 with commit b615238e5bc01e13dc0610febddc1ca99bab1df6
	Issue introduced in 5.8 with commit a52bcc919b14c9d78f03b2b4ff604e5ca69c7e6d and fixed in 6.1.21 with commit 3517584cf1b35bd02f4a90267ddf9dcf17bd9c87
	Issue introduced in 5.8 with commit a52bcc919b14c9d78f03b2b4ff604e5ca69c7e6d and fixed in 6.2.8 with commit c9ca2257150272df1b8d9ebe5059197ffea6e913
	Issue introduced in 5.8 with commit a52bcc919b14c9d78f03b2b4ff604e5ca69c7e6d and fixed in 6.3 with commit 13085e1b5cab8ad802904d72e6a6dae85ae0cd20

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-2023-53233
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/smc_core.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/9708efad9ba5095b9bb7916e11a135b3bd66c071
	https://git.kernel.org/stable/c/b615238e5bc01e13dc0610febddc1ca99bab1df6
	https://git.kernel.org/stable/c/3517584cf1b35bd02f4a90267ddf9dcf17bd9c87
	https://git.kernel.org/stable/c/c9ca2257150272df1b8d9ebe5059197ffea6e913
	https://git.kernel.org/stable/c/13085e1b5cab8ad802904d72e6a6dae85ae0cd20

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