linux-cve-announce - CVE-2023-53088: mptcp: fix UaF in listener shutdown

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Message-ID: <2025050219-CVE-2023-53088-501c@gregkh>
Date: Fri,  2 May 2025 17:55:53 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53088: mptcp: fix UaF in listener shutdown

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

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

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

mptcp: fix UaF in listener shutdown

As reported by Christoph after having refactored the passive
socket initialization, the mptcp listener shutdown path is prone
to an UaF issue.

  BUG: KASAN: use-after-free in _raw_spin_lock_bh+0x73/0xe0
  Write of size 4 at addr ffff88810cb23098 by task syz-executor731/1266

  CPU: 1 PID: 1266 Comm: syz-executor731 Not tainted 6.2.0-rc59af4eaa31c1f6c00c8f1e448ed99a45c66340dd5 #6
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  Call Trace:
   <TASK>
   dump_stack_lvl+0x6e/0x91
   print_report+0x16a/0x46f
   kasan_report+0xad/0x130
   kasan_check_range+0x14a/0x1a0
   _raw_spin_lock_bh+0x73/0xe0
   subflow_error_report+0x6d/0x110
   sk_error_report+0x3b/0x190
   tcp_disconnect+0x138c/0x1aa0
   inet_child_forget+0x6f/0x2e0
   inet_csk_listen_stop+0x209/0x1060
   __mptcp_close_ssk+0x52d/0x610
   mptcp_destroy_common+0x165/0x640
   mptcp_destroy+0x13/0x80
   __mptcp_destroy_sock+0xe7/0x270
   __mptcp_close+0x70e/0x9b0
   mptcp_close+0x2b/0x150
   inet_release+0xe9/0x1f0
   __sock_release+0xd2/0x280
   sock_close+0x15/0x20
   __fput+0x252/0xa20
   task_work_run+0x169/0x250
   exit_to_user_mode_prepare+0x113/0x120
   syscall_exit_to_user_mode+0x1d/0x40
   do_syscall_64+0x48/0x90
   entry_SYSCALL_64_after_hwframe+0x72/0xdc

The msk grace period can legitly expire in between the last
reference count dropped in mptcp_subflow_queue_clean() and
the later eventual access in inet_csk_listen_stop()

After the previous patch we don't need anymore special-casing
msk listener socket cleanup: the mptcp worker will process each
of the unaccepted msk sockets.

Just drop the now unnecessary code.

Please note this commit depends on the two parent ones:

  mptcp: refactor passive socket initialization
  mptcp: use the workqueue to destroy unaccepted sockets

The Linux kernel CVE team has assigned CVE-2023-53088 to this issue.


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

	Issue introduced in 5.19 with commit 6aeed9045071f2252ff4e98fc13d1e304f33e5b0 and fixed in 6.1.22 with commit 5564be74a22a61855f8b8c100d8c4abb003bb792
	Issue introduced in 5.19 with commit 6aeed9045071f2252ff4e98fc13d1e304f33e5b0 and fixed in 6.2.8 with commit 0f4f4cf5d32f10543deb946a37111e714579511e
	Issue introduced in 5.19 with commit 6aeed9045071f2252ff4e98fc13d1e304f33e5b0 and fixed in 6.3 with commit 0a3f4f1f9c27215e4ddcd312558342e57b93e518
	Issue introduced in 5.18.10 with commit a8a3e95c74e48c2c9b07b81fafda9122993f2e12

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-2023-53088
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/mptcp/protocol.c
	net/mptcp/protocol.h
	net/mptcp/subflow.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/5564be74a22a61855f8b8c100d8c4abb003bb792
	https://git.kernel.org/stable/c/0f4f4cf5d32f10543deb946a37111e714579511e
	https://git.kernel.org/stable/c/0a3f4f1f9c27215e4ddcd312558342e57b93e518