[src/trunk]: src/sys/netinet Only check that the offset < sizeof(struct ip) i...

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

details:   https://anonhg.NetBSD.org/src/rev/636c55a556a7
branches:  trunk
changeset: 804807:636c55a556a7
user:      christos <christos%NetBSD.org@localhost>
date:      Sun Nov 30 18:15:41 2014 +0000

description:
Only check that the offset < sizeof(struct ip) if nxt != 0, i.e. in the
tcp and udp cases. From kre.
XXX: pullup 7

diffstat:

 sys/netinet/in4_cksum.c |  11 ++++++-----
 1 files changed, 6 insertions(+), 5 deletions(-)

diffs (39 lines):

diff -r 234b11f9734a -r 636c55a556a7 sys/netinet/in4_cksum.c
--- a/sys/netinet/in4_cksum.c   Sun Nov 30 15:54:34 2014 +0000
+++ b/sys/netinet/in4_cksum.c   Sun Nov 30 18:15:41 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: in4_cksum.c,v 1.19 2013/03/12 21:54:36 christos Exp $  */
+/*     $NetBSD: in4_cksum.c,v 1.20 2014/11/30 18:15:41 christos Exp $  */
 
 /*-
  * Copyright (c) 2008 Joerg Sonnenberger <joerg%NetBSD.org@localhost>.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: in4_cksum.c,v 1.19 2013/03/12 21:54:36 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: in4_cksum.c,v 1.20 2014/11/30 18:15:41 christos Exp $");
 
 #include <sys/param.h>
 #include <sys/mbuf.h>
@@ -58,9 +58,6 @@
        uint32_t sum;
        uint16_t *w;
 
-       if (__predict_false(off < sizeof(struct ip)))
-               PANIC("%s: offset %d too short for IP header %zu", __func__,
-                   off, sizeof(struct ip));
        if (__predict_false(m->m_len < sizeof(struct ip)))
                PANIC("%s: mbuf %d too short for IP header %zu", __func__,
                    m->m_len, sizeof(struct ip));
@@ -68,6 +65,10 @@
        if (nxt == 0)
                return cpu_in_cksum(m, len, off, 0);
 
+       if (__predict_false(off < sizeof(struct ip)))
+               PANIC("%s: offset %d too short for IP header %zu", __func__,
+                   off, sizeof(struct ip));
+
        /*
         * Compute the equivalent of:
         * struct ipovly ip;