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.