[src/trunk]: src/sys/net Correct frame padding length

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

details:   https://anonhg.NetBSD.org/src/rev/a8a1a2f4c59b
branches:  trunk
changeset: 336987:a8a1a2f4c59b
user:      ozaki-r <ozaki-r%NetBSD.org@localhost>
date:      Sun Mar 29 13:30:43 2015 +0000

description:
Correct frame padding length

vlan pads a frame with zeros up to 68 bytes
(ETHER_MIN_LEN + ETHER_VLAN_ENCAP_LEN). It expects
that even if the frame is untagged, it keeps 64 bytes
at least. However, it lacks concern about CRC
(4 bytes). So a sending frame can be 72 (68 + 4) bytes.

PR 49788

diffstat:

 sys/net/if_vlan.c |  9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)

diffs (31 lines):

diff -r 4bcbf654764f -r a8a1a2f4c59b sys/net/if_vlan.c
--- a/sys/net/if_vlan.c Sun Mar 29 12:00:02 2015 +0000
+++ b/sys/net/if_vlan.c Sun Mar 29 13:30:43 2015 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_vlan.c,v 1.79 2015/01/16 10:36:14 ozaki-r Exp $     */
+/*     $NetBSD: if_vlan.c,v 1.80 2015/03/29 13:30:43 ozaki-r Exp $     */
 
 /*-
  * Copyright (c) 2000, 2001 The NetBSD Foundation, Inc.
@@ -78,7 +78,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_vlan.c,v 1.79 2015/01/16 10:36:14 ozaki-r Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_vlan.c,v 1.80 2015/03/29 13:30:43 ozaki-r Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_inet.h"
@@ -806,9 +806,10 @@
                                 * after deleting a tag.
                                 */
                                if (m->m_pkthdr.len <
-                                   (ETHER_MIN_LEN + ETHER_VLAN_ENCAP_LEN)) {
+                                   (ETHER_MIN_LEN - ETHER_CRC_LEN +
+                                    ETHER_VLAN_ENCAP_LEN)) {
                                        m_copyback(m, m->m_pkthdr.len,
-                                           (ETHER_MIN_LEN +
+                                           (ETHER_MIN_LEN - ETHER_CRC_LEN +
                                             ETHER_VLAN_ENCAP_LEN) -
                                             m->m_pkthdr.len,
                                            vlan_zero_pad_buff);