linux-cve-announce - CVE-2022-49198: mptcp: Fix crash due to tcp_tsorted_anchor was initialized before release skb

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Message-ID: <2025022617-CVE-2022-49198-98a2@gregkh>
Date: Wed, 26 Feb 2025 02:56:43 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2022-49198: mptcp: Fix crash due to tcp_tsorted_anchor was initialized before release skb

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

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

mptcp: Fix crash due to tcp_tsorted_anchor was initialized before release skb

Got crash when doing pressure test of mptcp:

===========================================================================
dst_release: dst:ffffa06ce6e5c058 refcnt:-1
kernel tried to execute NX-protected page - exploit attempt? (uid: 0)
BUG: unable to handle kernel paging request at ffffa06ce6e5c058
PGD 190a01067 P4D 190a01067 PUD 43fffb067 PMD 22e403063 PTE 8000000226e5c063
Oops: 0011 [#1] SMP PTI
CPU: 7 PID: 7823 Comm: kworker/7:0 Kdump: loaded Tainted: G            E
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.2.1 04/01/2014
Call Trace:
 ? skb_release_head_state+0x68/0x100
 ? skb_release_all+0xe/0x30
 ? kfree_skb+0x32/0xa0
 ? mptcp_sendmsg_frag+0x57e/0x750
 ? __mptcp_retrans+0x21b/0x3c0
 ? __switch_to_asm+0x35/0x70
 ? mptcp_worker+0x25e/0x320
 ? process_one_work+0x1a7/0x360
 ? worker_thread+0x30/0x390
 ? create_worker+0x1a0/0x1a0
 ? kthread+0x112/0x130
 ? kthread_flush_work_fn+0x10/0x10
 ? ret_from_fork+0x35/0x40
===========================================================================

In __mptcp_alloc_tx_skb skb was allocated and skb->tcp_tsorted_anchor will
be initialized, in under memory pressure situation sk_wmem_schedule will
return false and then kfree_skb. In this case skb->_skb_refdst is not null
because_skb_refdst and tcp_tsorted_anchor are stored in the same mem, and
kfree_skb will try to release dst and cause crash.

The Linux kernel CVE team has assigned CVE-2022-49198 to this issue.


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

	Issue introduced in 5.16 with commit f70cad1085d1e01d3ec73c1078405f906237feee and fixed in 5.16.19 with commit 752add6f5ce5305e55d8bda4ac8d69be3a09f14d
	Issue introduced in 5.16 with commit f70cad1085d1e01d3ec73c1078405f906237feee and fixed in 5.17.2 with commit 4d54181eba4b077fb74033a7186898ad4000a7a5
	Issue introduced in 5.16 with commit f70cad1085d1e01d3ec73c1078405f906237feee and fixed in 5.18 with commit 3ef3905aa3b5b3e222ee6eb0210bfd999417a8cc

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-2022-49198
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


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/af61a8f7603926c26158153d0a0755764d82657c
	https://git.kernel.org/stable/c/752add6f5ce5305e55d8bda4ac8d69be3a09f14d
	https://git.kernel.org/stable/c/4d54181eba4b077fb74033a7186898ad4000a7a5
	https://git.kernel.org/stable/c/3ef3905aa3b5b3e222ee6eb0210bfd999417a8cc