CVE-2026-97601: ieee802154: 6lowpan: fix NULL dereference in lowpan_newlink

CVE-2026-97601: ieee802154: 6lowpan: fix NULL dereference in lowpan_newlink

[Greg Kroah-Hartman]

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

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

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

ieee802154: 6lowpan: fix NULL dereference in lowpan_newlink

TUNSETLINK allows a TUN device to change its link-layer type to
ARPHRD_IEEE802154 without initializing ieee802154_ptr. lowpan_newlink()
checks only the device type before dereferencing the pointer, so an
RTM_NEWLINK request can trigger a NULL pointer dereference.

Reject devices without ieee802154_ptr along with devices of the wrong type.

The Linux kernel CVE team has assigned CVE-2026-97601 to this issue.


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

	Issue introduced in 4.3 with commit 51e0e5d8124ece158927a4c2288c0929d3b53aa3 and fixed in 6.12.111 with commit 1c7710af7ad9532b534f1c134c11b04dbe4e0e0f
	Issue introduced in 4.3 with commit 51e0e5d8124ece158927a4c2288c0929d3b53aa3 and fixed in 6.18.53 with commit 98ce5a42cde780ee0e40378607d4428c8fc12ec1
	Issue introduced in 4.3 with commit 51e0e5d8124ece158927a4c2288c0929d3b53aa3 and fixed in 7.2.7 with commit 8528da2333ce05cf627f93425f9d05efb08b3146
	Issue introduced in 4.3 with commit 51e0e5d8124ece158927a4c2288c0929d3b53aa3 and fixed in 7.3-rc3 with commit bf79662bc85e820ac3b846e2f347da29fbf6ac95

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-2026-97601
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/ieee802154/6lowpan/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/1c7710af7ad9532b534f1c134c11b04dbe4e0e0f
	https://git.kernel.org/stable/c/98ce5a42cde780ee0e40378607d4428c8fc12ec1
	https://git.kernel.org/stable/c/8528da2333ce05cf627f93425f9d05efb08b3146
	https://git.kernel.org/stable/c/bf79662bc85e820ac3b846e2f347da29fbf6ac95