CVE-2026-68336: bonding: fix devconf_all NULL dereference when IPv6 is disabled

CVE-2026-68336: bonding: fix devconf_all NULL dereference when IPv6 is disabled

[Greg Kroah-Hartman]

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

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

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

bonding: fix devconf_all NULL dereference when IPv6 is disabled

When booting with the 'ipv6.disable=1' parameter, the devconf_all is
never initialized because inet6_init() exits before addrconf_init() is
called which initializes it. bond_send_validate(), however, will still
call bond_ns_send_all() even ipv6 is indeed disabled. It will lead to
NULL derefence of net->ipv6.devconf_all in ip6_pol_route().

 BUG: kernel NULL pointer dereference, address: 000000000000000c
 [...]
 Workqueue: bond0 bond_arp_monitor [bonding]
 RIP: 0010:ip6_pol_route+0x69/0x480
 [...]
 Call Trace:
  <TASK>
  ? srso_return_thunk+0x5/0x5f
  ? __pfx_ip6_pol_route_output+0x10/0x10
  fib6_rule_lookup+0xfe/0x260
  ? wakeup_preempt+0x8a/0x90
  ? srso_return_thunk+0x5/0x5f
  ? srso_return_thunk+0x5/0x5f
  ? sched_balance_rq+0x369/0x810
  ip6_route_output_flags+0xd7/0x170
  bond_ns_send_all+0xde/0x280 [bonding]
  bond_ab_arp_probe+0x296/0x320 [bonding]
  ? srso_return_thunk+0x5/0x5f
  bond_activebackup_arp_mon+0xb4/0x2c0 [bonding]
  process_one_work+0x196/0x370
  worker_thread+0x1af/0x320
  ? srso_return_thunk+0x5/0x5f
  ? __pfx_worker_thread+0x10/0x10
  kthread+0xe3/0x120
  ? __pfx_kthread+0x10/0x10
  ret_from_fork+0x199/0x260
  ? __pfx_kthread+0x10/0x10
  ret_from_fork_asm+0x1a/0x30
  </TASK>

Fix this by adding ipv6_mod_enabled() condition check in the caller.

The Linux kernel CVE team has assigned CVE-2026-68336 to this issue.


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

	Issue introduced in 5.18 with commit 4e24be018eb9dbcefa4b01c07e298b147dc1a4d7 and fixed in 6.6.148 with commit 2a4bad24ac5296b262ad821aa5e08bb265e6b154
	Issue introduced in 5.18 with commit 4e24be018eb9dbcefa4b01c07e298b147dc1a4d7 and fixed in 6.12.101 with commit 690ce66782778e8c4b1fdd79c0b0890a100e9522
	Issue introduced in 5.18 with commit 4e24be018eb9dbcefa4b01c07e298b147dc1a4d7 and fixed in 6.18.42 with commit 992dce02bdabbd9883255ea9b36494e34a7821d7
	Issue introduced in 5.18 with commit 4e24be018eb9dbcefa4b01c07e298b147dc1a4d7 and fixed in 7.1.6 with commit 738039ad21e20ca2c5bbde2f5a4f5ad5fb718038
	Issue introduced in 5.18 with commit 4e24be018eb9dbcefa4b01c07e298b147dc1a4d7 and fixed in 7.2-rc5 with commit 1c975de3343cdef506f2eecc833cc1f14b0401c4

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-2026-68336
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_main.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/2a4bad24ac5296b262ad821aa5e08bb265e6b154
	https://git.kernel.org/stable/c/690ce66782778e8c4b1fdd79c0b0890a100e9522
	https://git.kernel.org/stable/c/992dce02bdabbd9883255ea9b36494e34a7821d7
	https://git.kernel.org/stable/c/738039ad21e20ca2c5bbde2f5a4f5ad5fb718038
	https://git.kernel.org/stable/c/1c975de3343cdef506f2eecc833cc1f14b0401c4