[src/trunk]: src/sys/netinet - always set both ip and ip6, otherwise a kernel...

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

details:   https://anonhg.NetBSD.org/src/rev/75e71bcaebbb
branches:  trunk
changeset: 973663:75e71bcaebbb
user:      christos <christos%NetBSD.org@localhost>
date:      Mon Jul 06 18:49:12 2020 +0000

description:
- always set both ip and ip6, otherwise a kernel assertion can be triggered
- move alignment early so that we do less work

diffstat:

 sys/netinet/tcp_input.c |  44 +++++++++++++++++++-------------------------
 1 files changed, 19 insertions(+), 25 deletions(-)

diffs (94 lines):

diff -r e1912fec4546 -r 75e71bcaebbb sys/netinet/tcp_input.c
--- a/sys/netinet/tcp_input.c   Mon Jul 06 18:47:02 2020 +0000
+++ b/sys/netinet/tcp_input.c   Mon Jul 06 18:49:12 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tcp_input.c,v 1.417 2019/11/16 10:15:10 maxv Exp $     */
+/*     $NetBSD: tcp_input.c,v 1.418 2020/07/06 18:49:12 christos Exp $ */
 
 /*
  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -148,7 +148,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: tcp_input.c,v 1.417 2019/11/16 10:15:10 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: tcp_input.c,v 1.418 2020/07/06 18:49:12 christos Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_inet.h"
@@ -1240,15 +1240,29 @@
        }
 
        /*
+        * Enforce alignment requirements that are violated in
+        * some cases, see kern/50766 for details.
+        */
+       if (TCP_HDR_ALIGNED_P(th) == 0) {
+               m = m_copyup(m, off + sizeof(struct tcphdr), 0);
+               if (m == NULL) {
+                       TCP_STATINC(TCP_STAT_RCVSHORT);
+                       return;
+               }
+               th = (struct tcphdr *)(mtod(m, char *) + off);
+       }
+       KASSERT(TCP_HDR_ALIGNED_P(th));
+
+       /*
         * Get IP and TCP header.
         * Note: IP leaves IP header in first mbuf.
         */
        ip = mtod(m, struct ip *);
+#ifdef INET6
+       ip6 = mtod(m, struct ip6_hdr *);
+#endif
        switch (ip->ip_v) {
        case 4:
-#ifdef INET6
-               ip6 = NULL;
-#endif
                af = AF_INET;
                iphlen = sizeof(struct ip);
 
@@ -1263,10 +1277,8 @@
                break;
 #ifdef INET6
        case 6:
-               ip = NULL;
                iphlen = sizeof(struct ip6_hdr);
                af = AF_INET6;
-               ip6 = mtod(m, struct ip6_hdr *);
 
                /*
                 * Be proactive about unspecified IPv6 address in source.
@@ -1301,23 +1313,6 @@
                return;
        }
 
-       /*
-        * Enforce alignment requirements that are violated in
-        * some cases, see kern/50766 for details.
-        */
-       if (TCP_HDR_ALIGNED_P(th) == 0) {
-               m = m_copyup(m, off + sizeof(struct tcphdr), 0);
-               if (m == NULL) {
-                       TCP_STATINC(TCP_STAT_RCVSHORT);
-                       return;
-               }
-               ip = mtod(m, struct ip *);
-#ifdef INET6
-               ip6 = mtod(m, struct ip6_hdr *);
-#endif
-               th = (struct tcphdr *)(mtod(m, char *) + off);
-       }
-       KASSERT(TCP_HDR_ALIGNED_P(th));
 
        /*
         * Check that TCP offset makes sense, pull out TCP options and
@@ -1515,7 +1510,6 @@
                        m_freem(in6p->in6p_options);
                        in6p->in6p_options = NULL;
                }
-               KASSERT(ip6 != NULL);
                ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m);
        }
 #endif