kern/49427: netinet/in4_cksum.c message flood

[Hauke Fath <hauke%Espresso.Rhein-Neckar.DE@localhost>]

>Number:         49427
>Category:       kern
>Synopsis:       netinet/in4_cksum.c message flood
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Nov 28 21:20:00 +0000 2014
>Originator:     Hauke Fath
>Release:        NetBSD 7.0_BETA
>Organization:
Falling Raindrops
>Environment:
	
	
System: NetBSD pizza.causeuse.org 7.0_BETA NetBSD 7.0_BETA (BLACKBOX-$Revision: 1.85 $) #0: Thu Nov 27 17:56:03 CET 2014 hauke%pizza.causeuse.org@localhost:/var/obj/netbsd-builds/7/amd64/sys/arch/amd64/compile/BLACKBOX amd64
Architecture: x86_64
Machine: amd64
>Description:

	After the upgrade to netbsd-7, a router machine floods the
	console with an endless stream of in4_cksum: offset 0 too
	short for IP header 20

	and syslogd(8) is hogging a cpu core at 100%.

	The machine shows this with both pf and npf active. If it
	matters, /etc/sysctl.conf has

net.inet.ip.do_loopback_cksum=1
net.inet.tcp.do_loopback_cksum=1
net.inet.udp.do_loopback_cksum=1
net.inet6.tcp6.do_loopback_cksum=1
net.inet6.udp6.do_loopback_cksum=1


>How-To-Repeat:

	Install netbsd-7 on a filtering router.

>Fix:
	Yes, please.

>Unformatted: