linux-cve-announce - CVE-2023-54114: net: nsh: Use correct mac_offset to unwind gso skb in nsh_gso

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Message-ID: <2025122414-CVE-2023-54114-8362@gregkh>
Date: Wed, 24 Dec 2025 14:07:11 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-54114: net: nsh: Use correct mac_offset to unwind gso skb in nsh_gso_segment()

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

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

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

net: nsh: Use correct mac_offset to unwind gso skb in nsh_gso_segment()

As the call trace shows, skb_panic was caused by wrong skb->mac_header
in nsh_gso_segment():

invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 3 PID: 2737 Comm: syz Not tainted 6.3.0-next-20230505 #1
RIP: 0010:skb_panic+0xda/0xe0
call Trace:
 skb_push+0x91/0xa0
 nsh_gso_segment+0x4f3/0x570
 skb_mac_gso_segment+0x19e/0x270
 __skb_gso_segment+0x1e8/0x3c0
 validate_xmit_skb+0x452/0x890
 validate_xmit_skb_list+0x99/0xd0
 sch_direct_xmit+0x294/0x7c0
 __dev_queue_xmit+0x16f0/0x1d70
 packet_xmit+0x185/0x210
 packet_snd+0xc15/0x1170
 packet_sendmsg+0x7b/0xa0
 sock_sendmsg+0x14f/0x160

The root cause is:
nsh_gso_segment() use skb->network_header - nhoff to reset mac_header
in skb_gso_error_unwind() if inner-layer protocol gso fails.
However, skb->network_header may be reset by inner-layer protocol
gso function e.g. mpls_gso_segment. skb->mac_header reset by the
inaccurate network_header will be larger than skb headroom.

nsh_gso_segment
    nhoff = skb->network_header - skb->mac_header;
    __skb_pull(skb,nsh_len)
    skb_mac_gso_segment
        mpls_gso_segment
            skb_reset_network_header(skb);//skb->network_header+=nsh_len
            return -EINVAL;
    skb_gso_error_unwind
        skb_push(skb, nsh_len);
        skb->mac_header = skb->network_header - nhoff;
        // skb->mac_header > skb->headroom, cause skb_push panic

Use correct mac_offset to restore mac_header and get rid of nhoff.

The Linux kernel CVE team has assigned CVE-2023-54114 to this issue.


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

	Issue introduced in 4.14 with commit c411ed854584a71b0e86ac3019b60e4789d88086 and fixed in 4.14.316 with commit 2f88c8d38ecf5ed0273f99a067246899ba499eb2
	Issue introduced in 4.14 with commit c411ed854584a71b0e86ac3019b60e4789d88086 and fixed in 4.19.284 with commit d2309e0cb27b6871b273fbc1725e93be62570d86
	Issue introduced in 4.14 with commit c411ed854584a71b0e86ac3019b60e4789d88086 and fixed in 5.4.244 with commit 435855b0831b351cb72cb38369ee33122ce9574c
	Issue introduced in 4.14 with commit c411ed854584a71b0e86ac3019b60e4789d88086 and fixed in 5.10.181 with commit 02b20e0bc0c2628539e9e518dc342787c3332de2
	Issue introduced in 4.14 with commit c411ed854584a71b0e86ac3019b60e4789d88086 and fixed in 5.15.113 with commit cdd8160dcda1fed2028a5f96575a84afc23aff7d
	Issue introduced in 4.14 with commit c411ed854584a71b0e86ac3019b60e4789d88086 and fixed in 6.1.30 with commit 6fbedf987b6b8ed54a50e2205d998eb2c8be72f9
	Issue introduced in 4.14 with commit c411ed854584a71b0e86ac3019b60e4789d88086 and fixed in 6.3.4 with commit cb38e62922aa3991793344b5a5870e7291c74a44
	Issue introduced in 4.14 with commit c411ed854584a71b0e86ac3019b60e4789d88086 and fixed in 6.4 with commit c83b49383b595be50647f0c764a48c78b5f3c4f8

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-2023-54114
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/nsh/nsh.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/2f88c8d38ecf5ed0273f99a067246899ba499eb2
	https://git.kernel.org/stable/c/d2309e0cb27b6871b273fbc1725e93be62570d86
	https://git.kernel.org/stable/c/435855b0831b351cb72cb38369ee33122ce9574c
	https://git.kernel.org/stable/c/02b20e0bc0c2628539e9e518dc342787c3332de2
	https://git.kernel.org/stable/c/cdd8160dcda1fed2028a5f96575a84afc23aff7d
	https://git.kernel.org/stable/c/6fbedf987b6b8ed54a50e2205d998eb2c8be72f9
	https://git.kernel.org/stable/c/cb38e62922aa3991793344b5a5870e7291c74a44
	https://git.kernel.org/stable/c/c83b49383b595be50647f0c764a48c78b5f3c4f8