[src/trunk]: src/sys/netinet6 inet6: nd6_na_input() now considers ln_state <=...

[roy <roy%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/294a01bc7802
branches:  trunk
changeset: 1009394:294a01bc7802
user:      roy <roy%NetBSD.org@localhost>
date:      Wed Apr 22 19:32:11 2020 +0000

description:
inet6: nd6_na_input() now considers ln_state <= ND6_LLINFO_INCOMPLETE

Otherwise if ln_state != ND6_LLINFO_INCOMPLETE and the is no lladdr
and this message was solicited then ln_state is set to ND6_LLINFO_REACHABLE
which could then cause a panic in nd6_resolve().
If ln_state > ND6_LLINFO_INCOMPLETE then it's assumed we have a lladdr.

Potentially this could have been triggered by the introduction of
ND6_LLINFO_PURGE in nd6.c r1.143 but also by the re-introduction of
ND6_LLINFO_INCOMPLETE in nd6.c r1.263.
Depending on the timing, it's technically possible to receive such
a message after the llentry is created with ND6_LLINFO_NOSTATE.

diffstat:

 sys/netinet6/nd6_nbr.c |  6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diffs (27 lines):

diff -r 6fd97b382c98 -r 294a01bc7802 sys/netinet6/nd6_nbr.c
--- a/sys/netinet6/nd6_nbr.c    Wed Apr 22 16:57:57 2020 +0000
+++ b/sys/netinet6/nd6_nbr.c    Wed Apr 22 19:32:11 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nd6_nbr.c,v 1.177 2020/03/09 21:20:56 roy Exp $        */
+/*     $NetBSD: nd6_nbr.c,v 1.178 2020/04/22 19:32:11 roy Exp $        */
 /*     $KAME: nd6_nbr.c,v 1.61 2001/02/10 16:06:14 jinmei Exp $        */
 
 /*
@@ -31,7 +31,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: nd6_nbr.c,v 1.177 2020/03/09 21:20:56 roy Exp $");
+__KERNEL_RCSID(0, "$NetBSD: nd6_nbr.c,v 1.178 2020/04/22 19:32:11 roy Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_inet.h"
@@ -735,7 +735,7 @@
                goto freeit;
 
        rt_cmd = 0;
-       if (ln->ln_state == ND6_LLINFO_INCOMPLETE) {
+       if (ln->ln_state <= ND6_LLINFO_INCOMPLETE) {
                /*
                 * If the link-layer has address, and no lladdr option came,
                 * discard the packet.