CVE-2026-98089: bonding: alb: fix uninitialized transport header access in alb_determine_nd()

CVE-2026-98089: bonding: alb: fix uninitialized transport header access in alb_determine_nd()

[Greg Kroah-Hartman]

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

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

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

bonding: alb: fix uninitialized transport header access in alb_determine_nd()

alb_determine_nd() uses icmp6_hdr(skb) to inspect ICMPv6 headers.
However, in xmit paths (e.g. packets sent via AF_PACKET / raw sockets
or forwarded packets), skb->transport_header is not guaranteed to be
initialized. While pskb_network_may_pull() ensures the packet data is
linear starting from the network header, it does not set or adjust the
transport header offset.

Dereferencing icmp6_hdr(skb) can therefore access out-of-bounds memory.

Fetch the icmp6hdr directly after ipv6hdr following pskb_network_may_pull(),
and reload ipv6hdr in case pskb_may_pull() reallocated skb->head.
Also remove the unused bond argument from alb_determine_nd().

The Linux kernel CVE team has assigned CVE-2026-98089 to this issue.


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

	Issue introduced in 5.18 with commit 0da8aa00bfcfeb3f4e6537dd8e2001e0727ba549 and fixed in 6.12.111 with commit e39cf90bd856443542b97933289749fca07476bf
	Issue introduced in 5.18 with commit 0da8aa00bfcfeb3f4e6537dd8e2001e0727ba549 and fixed in 6.18.53 with commit 27314f96d29b54e815e7a9b84c3273f1895e68e2
	Issue introduced in 5.18 with commit 0da8aa00bfcfeb3f4e6537dd8e2001e0727ba549 and fixed in 7.2.7 with commit 3b178894931a268c09126a5b53630f343e10e296
	Issue introduced in 5.18 with commit 0da8aa00bfcfeb3f4e6537dd8e2001e0727ba549 and fixed in 7.3-rc2 with commit 70f3995830d3f1e79faa14eb0605914f778feca9

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-2026-98089
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:
	drivers/net/bonding/bond_alb.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/e39cf90bd856443542b97933289749fca07476bf
	https://git.kernel.org/stable/c/27314f96d29b54e815e7a9b84c3273f1895e68e2
	https://git.kernel.org/stable/c/3b178894931a268c09126a5b53630f343e10e296
	https://git.kernel.org/stable/c/70f3995830d3f1e79faa14eb0605914f778feca9