Affected: Linux

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.