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Date:      Tue, 1 Sep 1998 19:11:17 -0700 (PDT)
From:      mccanne@cs.berkeley.edu
To:        freebsd-gnats-submit@FreeBSD.ORG
Subject:   kern/7802: outbound, fragmented multicast packets are mishandled at the data-link layer
Message-ID:  <199809020211.TAA14491@hub.freebsd.org>

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>Number:         7802
>Category:       kern
>Synopsis:       outbound, fragmented multicast packets are mishandled at the data-link layer
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:
>Keywords:
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Sep  1 19:20:01 PDT 1998
>Last-Modified:
>Originator:     Steven McCanne
>Organization:
University of California, Berkeley
>Release:        2.2.6
>Environment:
>Description:
Multicast packets larger than an MTU are fragmented and the fragments beyond the first have an incorrect MAC address because the M_MCAST bit is not copied into the fragmented packets.
>How-To-Repeat:
Run a multicast application on an ethernet that generates packets larger than the local net's MTU.  Run tcpdump -e and note that the ethernet MAC address does not conform to the IP-to-ethernet address mapping algorithm.
>Fix:
*** netinet/ip_output.c	1998/09/02 00:58:59	1.1
--- netinet/ip_output.c	1998/09/02 01:09:24
***************
*** 431,436 ****
--- 431,437 ----
  			ipstat.ips_odropped++;
  			goto sendorfree;
  		}
+ 		m->m_flags |= m0->m_flags & M_MCAST;
  		m->m_data += max_linkhdr;
  		mhip = mtod(m, struct ip *);
  		*mhip = *ip;

>Audit-Trail:
>Unformatted:

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