Message-ID: <2025022622-CVE-2022-49663-2213@gregkh>
Date: Wed, 26 Feb 2025 03:23:46 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2022-49663: tunnels: do not assume mac header is set in skb_tunnel_check_pmtu()

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

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

tunnels: do not assume mac header is set in skb_tunnel_check_pmtu()

Recently added debug in commit f9aefd6b2aa3 ("net: warn if mac header
was not set") caught a bug in skb_tunnel_check_pmtu(), as shown
in this syzbot report [1].

In ndo_start_xmit() paths, there is really no need to use skb->mac_header,
because skb->data is supposed to point at it.

[1] WARNING: CPU: 1 PID: 8604 at include/linux/skbuff.h:2784 skb_mac_header_len include/linux/skbuff.h:2784 [inline]
WARNING: CPU: 1 PID: 8604 at include/linux/skbuff.h:2784 skb_tunnel_check_pmtu+0x5de/0x2f90 net/ipv4/ip_tunnel_core.c:413
Modules linked in:
CPU: 1 PID: 8604 Comm: syz-executor.3 Not tainted 5.19.0-rc2-syzkaller-00443-g8720bd951b8e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:skb_mac_header_len include/linux/skbuff.h:2784 [inline]
RIP: 0010:skb_tunnel_check_pmtu+0x5de/0x2f90 net/ipv4/ip_tunnel_core.c:413
Code: 00 00 00 00 fc ff df 4c 89 fa 48 c1 ea 03 80 3c 02 00 0f 84 b9 fe ff ff 4c 89 ff e8 7c 0f d7 f9 e9 ac fe ff ff e8 c2 13 8a f9 <0f> 0b e9 28 fc ff ff e8 b6 13 8a f9 48 8b 54 24 70 48 b8 00 00 00
RSP: 0018:ffffc90002e4f520 EFLAGS: 00010212
RAX: 0000000000000324 RBX: ffff88804d5fd500 RCX: ffffc90005b52000
RDX: 0000000000040000 RSI: ffffffff87f05e3e RDI: 0000000000000003
RBP: ffffc90002e4f650 R08: 0000000000000003 R09: 000000000000ffff
R10: 000000000000ffff R11: 0000000000000000 R12: 000000000000ffff
R13: 0000000000000000 R14: 000000000000ffcd R15: 000000000000001f
FS: 00007f3babba9700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000080 CR3: 0000000075319000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
geneve_xmit_skb drivers/net/geneve.c:927 [inline]
geneve_xmit+0xcf8/0x35d0 drivers/net/geneve.c:1107
__netdev_start_xmit include/linux/netdevice.h:4805 [inline]
netdev_start_xmit include/linux/netdevice.h:4819 [inline]
__dev_direct_xmit+0x500/0x730 net/core/dev.c:4309
dev_direct_xmit include/linux/netdevice.h:3007 [inline]
packet_direct_xmit+0x1b8/0x2c0 net/packet/af_packet.c:282
packet_snd net/packet/af_packet.c:3073 [inline]
packet_sendmsg+0x21f4/0x55d0 net/packet/af_packet.c:3104
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:734
____sys_sendmsg+0x6eb/0x810 net/socket.c:2489
___sys_sendmsg+0xf3/0x170 net/socket.c:2543
__sys_sendmsg net/socket.c:2572 [inline]
__do_sys_sendmsg net/socket.c:2581 [inline]
__se_sys_sendmsg net/socket.c:2579 [inline]
__x64_sys_sendmsg+0x132/0x220 net/socket.c:2579
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x46/0xb0
RIP: 0033:0x7f3baaa89109
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:00007f3babba9168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f3baab9bf60 RCX: 00007f3baaa89109
RDX: 0000000000000000 RSI: 0000000020000a00 RDI: 0000000000000003
RBP: 00007f3baaae305d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe74f2543f R14: 00007f3babba9300 R15: 0000000000022000
</TASK>

The Linux kernel CVE team has assigned CVE-2022-49663 to this issue.


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

	Issue introduced in 5.9 with commit 4cb47a8644cc9eb8ec81190a50e79e6530d0297f and fixed in 5.10.129 with commit 59c51c3b545128a92ebfb6dbae990d3abee110e7
	Issue introduced in 5.9 with commit 4cb47a8644cc9eb8ec81190a50e79e6530d0297f and fixed in 5.15.53 with commit 674a641e5b67e16ba3112eacd680ff87b38539de
	Issue introduced in 5.9 with commit 4cb47a8644cc9eb8ec81190a50e79e6530d0297f and fixed in 5.18.10 with commit 32dcf62efa0003f92a976aea0c57f118e689de8b
	Issue introduced in 5.9 with commit 4cb47a8644cc9eb8ec81190a50e79e6530d0297f and fixed in 5.19 with commit 853a7614880231747040cada91d2b8d2e995c51a

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-2022-49663
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/ip_tunnel_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/59c51c3b545128a92ebfb6dbae990d3abee110e7
	https://git.kernel.org/stable/c/674a641e5b67e16ba3112eacd680ff87b38539de
	https://git.kernel.org/stable/c/32dcf62efa0003f92a976aea0c57f118e689de8b
	https://git.kernel.org/stable/c/853a7614880231747040cada91d2b8d2e995c51a

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