[src/trunk]: src/sys/dev/usb Add a check in smsc_tx_prepare for the mbuf bein...

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

details:   https://anonhg.NetBSD.org/src/rev/086bcb91aa79
branches:  trunk
changeset: 964660:086bcb91aa79
user:      skrll <skrll%NetBSD.org@localhost>
date:      Sun Aug 11 06:54:14 2019 +0000

description:
Add a check in smsc_tx_prepare for the mbuf being too big.  Discussed
with mrg@

diffstat:

 sys/dev/usb/if_smsc.c |  13 +++++++++----
 1 files changed, 9 insertions(+), 4 deletions(-)

diffs (42 lines):

diff -r 4fece27e0c51 -r 086bcb91aa79 sys/dev/usb/if_smsc.c
--- a/sys/dev/usb/if_smsc.c     Sun Aug 11 06:49:31 2019 +0000
+++ b/sys/dev/usb/if_smsc.c     Sun Aug 11 06:54:14 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_smsc.c,v 1.51 2019/08/10 02:17:36 mrg Exp $ */
+/*     $NetBSD: if_smsc.c,v 1.52 2019/08/11 06:54:14 skrll Exp $       */
 
 /*     $OpenBSD: if_smsc.c,v 1.4 2012/09/27 12:38:11 jsg Exp $ */
 /*     $FreeBSD: src/sys/dev/usb/net/if_smsc.c,v 1.1 2012/08/15 04:03:55 gonzo Exp $ */
@@ -61,7 +61,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_smsc.c,v 1.51 2019/08/10 02:17:36 mrg Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_smsc.c,v 1.52 2019/08/11 06:54:14 skrll Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_usb.h"
@@ -1048,6 +1048,11 @@
 
        usbnet_isowned_tx(un);
 
+       const size_t hdrsz = sizeof(txhdr) * 2;
+
+       if ((unsigned)m->m_pkthdr.len > un->un_tx_bufsz - hdrsz)
+               return 0;
+
        /*
         * Each frame is prefixed with two 32-bit values describing the
         * length of the packet and buffer.
@@ -1059,9 +1064,9 @@
 
        txhdr = SMSC_TX_CTRL_1_PKT_LENGTH(m->m_pkthdr.len);
        txhdr = htole32(txhdr);
-       memcpy(c->unc_buf + 4, &txhdr, sizeof(txhdr));
+       memcpy(c->unc_buf + sizeof(txhdr), &txhdr, sizeof(txhdr));
 
-       frm_len += 8;
+       frm_len += hdrsz;
 
        /* Next copy in the actual packet */
        m_copydata(m, 0, m->m_pkthdr.len, c->unc_buf + frm_len);