[src/trunk]: src/sys/netinet6 Fix use-after-free: if m_pullup fails the (free...

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

details:   https://anonhg.NetBSD.org/src/rev/f41e686fddb1
branches:  trunk
changeset: 828369:f41e686fddb1
user:      maxv <maxv%NetBSD.org@localhost>
date:      Sun Dec 10 09:06:46 2017 +0000

description:
Fix use-after-free: if m_pullup fails the (freed) mbuf is pushed on the
ip6_pktq queue and re-processed later. Return 1 to say "processed and
freed".

diffstat:

 sys/netinet6/ip6_flow.c |  12 ++++--------
 1 files changed, 4 insertions(+), 8 deletions(-)

diffs (33 lines):

diff -r 683886845351 -r f41e686fddb1 sys/netinet6/ip6_flow.c
--- a/sys/netinet6/ip6_flow.c   Sun Dec 10 08:56:23 2017 +0000
+++ b/sys/netinet6/ip6_flow.c   Sun Dec 10 09:06:46 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ip6_flow.c,v 1.35 2017/11/17 07:37:12 ozaki-r Exp $    */
+/*     $NetBSD: ip6_flow.c,v 1.36 2017/12/10 09:06:46 maxv Exp $       */
 
 /*-
  * Copyright (c) 2007 The NetBSD Foundation, Inc.
@@ -38,7 +38,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ip6_flow.c,v 1.35 2017/11/17 07:37:12 ozaki-r Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ip6_flow.c,v 1.36 2017/12/10 09:06:46 maxv Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_net_mpsafe.h"
@@ -285,12 +285,8 @@
 
        if (IP6_HDR_ALIGNED_P(mtod(m, const void *)) == 0) {
                if ((m = m_copyup(m, sizeof(struct ip6_hdr),
-                               (max_linkhdr + 3) & ~3)) == NULL) {
-                       goto out;
-               }
-               *mp = m;
-       } else if (__predict_false(m->m_len < sizeof(struct ip6_hdr))) {
-               if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) {
+                   (max_linkhdr + 3) & ~3)) == NULL) {
+                       ret = 1;
                        goto out;
                }
                *mp = m;