linux-cve-announce - CVE-2022-49330: tcp: fix tcp_mtup_probe_success vs wrong snd

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Message-ID: <2025022639-CVE-2022-49330-199b@gregkh>
Date: Wed, 26 Feb 2025 03:10:04 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2022-49330: tcp: fix tcp_mtup_probe_success vs wrong snd_cwnd

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

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

tcp: fix tcp_mtup_probe_success vs wrong snd_cwnd

syzbot got a new report [1] finally pointing to a very old bug,
added in initial support for MTU probing.

tcp_mtu_probe() has checks about starting an MTU probe if
tcp_snd_cwnd(tp) >= 11.

But nothing prevents tcp_snd_cwnd(tp) to be reduced later
and before the MTU probe succeeds.

This bug would lead to potential zero-divides.

Debugging added in commit 40570375356c ("tcp: add accessors
to read/set tp->snd_cwnd") has paid off :)

While we are at it, address potential overflows in this code.

[1]
WARNING: CPU: 1 PID: 14132 at include/net/tcp.h:1219 tcp_mtup_probe_success+0x366/0x570 net/ipv4/tcp_input.c:2712
Modules linked in:
CPU: 1 PID: 14132 Comm: syz-executor.2 Not tainted 5.18.0-syzkaller-07857-gbabf0bb978e3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:tcp_snd_cwnd_set include/net/tcp.h:1219 [inline]
RIP: 0010:tcp_mtup_probe_success+0x366/0x570 net/ipv4/tcp_input.c:2712
Code: 74 08 48 89 ef e8 da 80 17 f9 48 8b 45 00 65 48 ff 80 80 03 00 00 48 83 c4 30 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 aa b0 c5 f8 <0f> 0b e9 16 fe ff ff 48 8b 4c 24 08 80 e1 07 38 c1 0f 8c c7 fc ff
RSP: 0018:ffffc900079e70f8 EFLAGS: 00010287
RAX: ffffffff88c0f7f6 RBX: ffff8880756e7a80 RCX: 0000000000040000
RDX: ffffc9000c6c4000 RSI: 0000000000031f9e RDI: 0000000000031f9f
RBP: 0000000000000000 R08: ffffffff88c0f606 R09: ffffc900079e7520
R10: ffffed101011226d R11: 1ffff1101011226c R12: 1ffff1100eadcf50
R13: ffff8880756e72c0 R14: 1ffff1100eadcf89 R15: dffffc0000000000
FS:  00007f643236e700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1ab3f1e2a0 CR3: 0000000064fe7000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 tcp_clean_rtx_queue+0x223a/0x2da0 net/ipv4/tcp_input.c:3356
 tcp_ack+0x1962/0x3c90 net/ipv4/tcp_input.c:3861
 tcp_rcv_established+0x7c8/0x1ac0 net/ipv4/tcp_input.c:5973
 tcp_v6_do_rcv+0x57b/0x1210 net/ipv6/tcp_ipv6.c:1476
 sk_backlog_rcv include/net/sock.h:1061 [inline]
 __release_sock+0x1d8/0x4c0 net/core/sock.c:2849
 release_sock+0x5d/0x1c0 net/core/sock.c:3404
 sk_stream_wait_memory+0x700/0xdc0 net/core/stream.c:145
 tcp_sendmsg_locked+0x111d/0x3fc0 net/ipv4/tcp.c:1410
 tcp_sendmsg+0x2c/0x40 net/ipv4/tcp.c:1448
 sock_sendmsg_nosec net/socket.c:714 [inline]
 sock_sendmsg net/socket.c:734 [inline]
 __sys_sendto+0x439/0x5c0 net/socket.c:2119
 __do_sys_sendto net/socket.c:2131 [inline]
 __se_sys_sendto net/socket.c:2127 [inline]
 __x64_sys_sendto+0xda/0xf0 net/socket.c:2127
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0
RIP: 0033:0x7f6431289109
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f643236e168 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f643139c100 RCX: 00007f6431289109
RDX: 00000000d0d0c2ac RSI: 0000000020000080 RDI: 000000000000000a
RBP: 00007f64312e308d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff372533af R14: 00007f643236e300 R15: 0000000000022000

The Linux kernel CVE team has assigned CVE-2022-49330 to this issue.


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

	Issue introduced in 2.6.17 with commit 5d424d5a674f782d0659a3b66d951f412901faee and fixed in 4.9.318 with commit 29e13f6b38f0816af2012e0725507754e8f4569c
	Issue introduced in 2.6.17 with commit 5d424d5a674f782d0659a3b66d951f412901faee and fixed in 4.14.283 with commit 42726877453afdbe1508a8a96884ea907741d9a7
	Issue introduced in 2.6.17 with commit 5d424d5a674f782d0659a3b66d951f412901faee and fixed in 4.19.247 with commit f2845e1504a3bc4f3381394f057e8b63cb5f3f7a
	Issue introduced in 2.6.17 with commit 5d424d5a674f782d0659a3b66d951f412901faee and fixed in 5.4.198 with commit 602b338e3c3cd7f935f3f5011882961d074e5ac1
	Issue introduced in 2.6.17 with commit 5d424d5a674f782d0659a3b66d951f412901faee and fixed in 5.10.122 with commit 9ba2b4ac35935f05ac98cff722f36ba07d62270e
	Issue introduced in 2.6.17 with commit 5d424d5a674f782d0659a3b66d951f412901faee and fixed in 5.15.47 with commit 90385f2b65d0cd2b3b1ac8909f0cc6dd31062cfc
	Issue introduced in 2.6.17 with commit 5d424d5a674f782d0659a3b66d951f412901faee and fixed in 5.17.15 with commit aa7f333efd1138a68517a6a6a69ae540dd59d800
	Issue introduced in 2.6.17 with commit 5d424d5a674f782d0659a3b66d951f412901faee and fixed in 5.18.4 with commit 38ca71a24cd4845021eed35fd2594d89dba9a5a8
	Issue introduced in 2.6.17 with commit 5d424d5a674f782d0659a3b66d951f412901faee and fixed in 5.19 with commit 11825765291a93d8e7f44230da67b9f607c777bf

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-2022-49330
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/ipv4/tcp_input.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/29e13f6b38f0816af2012e0725507754e8f4569c
	https://git.kernel.org/stable/c/42726877453afdbe1508a8a96884ea907741d9a7
	https://git.kernel.org/stable/c/f2845e1504a3bc4f3381394f057e8b63cb5f3f7a
	https://git.kernel.org/stable/c/602b338e3c3cd7f935f3f5011882961d074e5ac1
	https://git.kernel.org/stable/c/9ba2b4ac35935f05ac98cff722f36ba07d62270e
	https://git.kernel.org/stable/c/90385f2b65d0cd2b3b1ac8909f0cc6dd31062cfc
	https://git.kernel.org/stable/c/aa7f333efd1138a68517a6a6a69ae540dd59d800
	https://git.kernel.org/stable/c/38ca71a24cd4845021eed35fd2594d89dba9a5a8
	https://git.kernel.org/stable/c/11825765291a93d8e7f44230da67b9f607c777bf