Date: Sun, 13 Jan 2008 16:27:16 GMT From: Bernd Heller <bdheller@users.sourceforge.net> To: freebsd-gnats-submit@FreeBSD.org Subject: kern/119635: Bad UDP packet checksum with em(4) and rxcsum/txcsum enabled Message-ID: <200801131627.m0DGRGAV098112@www.freebsd.org> Resent-Message-ID: <200801131630.m0DGU1CI034743@freefall.freebsd.org>
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>Number: 119635 >Category: kern >Synopsis: Bad UDP packet checksum with em(4) and rxcsum/txcsum enabled >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Sun Jan 13 16:30:01 UTC 2008 >Closed-Date: >Last-Modified: >Originator: Bernd Heller >Release: 7.0-RC1 >Organization: >Environment: FreeBSD 7.0-RC1 FreeBSD 7.0-RC1 #0: Mon Dec 24 10:10:07 UTC 2007 root@driscoll.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC amd64 >Description: I have an Intel Pro/1000 PT Desktop Adapter network card in that machine, and by default the em(4) driver has rxcsum/txcsum enabled. But the checksums for some UDP packets generated this way are wrong. I noticed this when trying to run avahi-daemon. It sends UDP multicast packets, but they were never recognized on the network. Only when using tcpdump did I notice the bad checksums. After I disabled rxcsum/txcsum on the interface all was working perfectly. I could reproduce the same issue in a VMware machine using FreeBSD 7.0-RC1 i386 and amd64. 6.2 seems to be unaffected. >How-To-Repeat: Run avahi-daemon to publish any services (it will do so by default) and analyze the UDP packages sent out. >Fix: Workaround: disable rxcsum/txcsum on the interface. >Release-Note: >Audit-Trail: >Unformatted:
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