[src/trunk]: src/sys/netinet6 Avoid double LIST_REMOVE which corrupts lists

[ozaki-r <ozaki-r%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/23d9eb9449e6
branches:  trunk
changeset: 362157:23d9eb9449e6
user:      ozaki-r <ozaki-r%NetBSD.org@localhost>
date:      Tue May 29 04:39:26 2018 +0000

description:
Avoid double LIST_REMOVE which corrupts lists

diffstat:

 sys/netinet6/mld6.c |  15 ++++++++-------
 1 files changed, 8 insertions(+), 7 deletions(-)

diffs (37 lines):

diff -r 775c251f440b -r 23d9eb9449e6 sys/netinet6/mld6.c
--- a/sys/netinet6/mld6.c       Tue May 29 04:38:59 2018 +0000
+++ b/sys/netinet6/mld6.c       Tue May 29 04:39:26 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: mld6.c,v 1.98 2018/05/29 04:38:59 ozaki-r Exp $        */
+/*     $NetBSD: mld6.c,v 1.99 2018/05/29 04:39:26 ozaki-r Exp $        */
 /*     $KAME: mld6.c,v 1.25 2001/01/16 14:14:18 itojun Exp $   */
 
 /*
@@ -102,7 +102,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: mld6.c,v 1.98 2018/05/29 04:38:59 ozaki-r Exp $");
+__KERNEL_RCSID(0, "$NetBSD: mld6.c,v 1.99 2018/05/29 04:39:26 ozaki-r Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_inet.h"
@@ -777,12 +777,13 @@
        KASSERT(in6m->in6m_refcount == 0);
 
        /*
-        * Unlink from list.  This must be done before mld_stop_listening
-        * because it releases in6_multilock and that allows someone to
-        * look up the removing in6m from the list and add a reference to the
-        * entry unexpectedly.
+        * Unlink from list if it's listed.  This must be done before
+        * mld_stop_listening because it releases in6_multilock and that allows
+        * someone to look up the removing in6m from the list and add a
+        * reference to the entry unexpectedly.
         */
-       LIST_REMOVE(in6m, in6m_entry);
+       if (in6_lookup_multi(&in6m->in6m_addr, in6m->in6m_ifp) != NULL)
+               LIST_REMOVE(in6m, in6m_entry);
 
        /*
         * No remaining claims to this record; let MLD6 know