kern/95665: "ping: sendto: No buffer space available" with TUN interface (easily reproducable with test program)

Johan Bolmsjö johan at nocrew.org
Wed Apr 12 20:40:14 UTC 2006


>Number:         95665
>Category:       kern
>Synopsis:       "ping: sendto: No buffer space available" with TUN interface (easily reproducable with test program)
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Apr 12 20:40:13 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     Johan Bolmsjö
>Release:        FreeBSD 6.0-RELEASE
>Organization:
>Environment:
FreeBSD matilda.nocrew.org 6.0-RELEASE FreeBSD 6.0-RELEASE #0: Sat Mar 18 15:18:13 CET 2006     root at matilda.nocrew.org:/usr/obj/usr/src/sys/SMP  i386
>Description:
I was playing a little with the TUN device under FreeBSD. I wanted to test the performance of the driver so I wrote a small ICMP echo reply server using the TUN device. When I ping flood this interface with a large amount of 1k byte packets the interface is "hung".

Pinging the interface shows the dreaded "ping: sendto: No buffer space available" message.

Pinging the interface from another PC on the LAN shows no problems what so ever. It seems that the sheer amount of traffic doing this localy is causing this problem. No successfull flood ping rounds have shown any dropped ping requests. What buffer space is out? This certainly looks like a bug to me.

I have a 200 line test program to reproduce this very easily. At the start of the test program there are detailed instructions on how to setup this test.

You can find it at:
http://six.nocrew.org/tmp/tun_icmp_echo_reply.c

>How-To-Repeat:
Run this test program:
http://six.nocrew.org/tmp/tun_icmp_echo_reply.c

There are detailed instructions at the top of the file on how to reproduce the problem.

>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:


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