pf: check if a group has a kif before dereferencing it
It's possible for interface groups to not have had a pfi_kkif assigned to
them, so before we pass that pointer to pfi_kkif_update() we must check if it's
actually set.
We've seen panics such as this, where we get an address update for an interface
that belongs to a group without associated pfi_kkif:
Tracing pid 12 tid 100034 td 0xfffff80100d2a000
kdb_enter() at kdb_enter+0x33/frame 0xfffffe0067eed340
panic() at panic+0x43/frame 0xfffffe0067eed3a0
trap_pfault() at trap_pfault+0x3c9/frame 0xfffffe0067eed3f0
calltrap() at calltrap+0x8/frame 0xfffffe0067eed3f0
- trap 0xc, rip = 0xffffffff8102ebd5, rsp = 0xfffffe0067eed4c0, rbp = 0xfffffe0067eed500 ---
pfi_kkif_update() at pfi_kkif_update+0x15/frame 0xfffffe0067eed500
pfi_kkif_update() at pfi_kkif_update+0x1fc/frame 0xfffffe0067eed550
pfi_ifaddr_event() at pfi_ifaddr_event+0x82/frame 0xfffffe0067eed5a0
srcaddr_change_event() at srcaddr_change_event+0xa7/frame 0xfffffe0067eed610
in6_update_ifa() at in6_update_ifa+0xd52/frame 0xfffffe0067eed790
in6_ifadd() at in6_ifadd+0x29a/frame 0xfffffe0067eed8b0
nd6_ra_input() at nd6_ra_input+0xf65/frame 0xfffffe0067eeda90
icmp6_input() at icmp6_input+0x3c8/frame 0xfffffe0067eedc10
ip6_input() at ip6_input+0xa15/frame 0xfffffe0067eedcf0
sppp_input() at sppp_input+0x502/frame 0xfffffe0067eedd80
pppoe_data_input() at pppoe_data_input+0x1e7/frame 0xfffffe0067eeddf0
swi_net() at swi_net+0x128/frame 0xfffffe0067eede60
ithread_loop() at ithread_loop+0x239/frame 0xfffffe0067eedef0
fork_exit() at fork_exit+0x7b/frame 0xfffffe0067eedf30
fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe0067eedf30
Note that pf doesn't assign pfi_kkif objects to groups created before pf has
fully started (see V_pf_vnet_active check in pfi_attach_group_event()), which is
one possible way for this to happen.
Reported by: garga
Sponsored by: Rubicon Communications, LLC ("Netgate")
(cherry picked from commit dc0cf0648c8d28ab4914c798a4cff8256ae94ee5)