SUMMARY: mclput panic

From: John R. Kilheffer (
Date: Thu May 02 1991 - 07:15:09 CDT

Seems I must have just missed a discussion this very same subject not all that
long ago. For the records, an excerpt of my original post was:

> Ok, I'm baffled. Anybody out there come across this problem?
> Today (5/1), at approximately 8:35am (EDT), every Sun box on our local net
> which was running SunOS 4.1 or SunOS 4.1.1 crashed with message:
> May 1 08:35:36 porsche vmunix: panic: mclput

Well, it seems this is a fairly well known problem (and nasty I might add since
when it occurs, it crashes every 4.1 and 4.1.1 box on the local network).

Fortunately, the fix is simple. Get yourself a copy of patch #100149-03.
Warning: Don't use 100149-01 as it has a bug. Below is a copy of the README
from the patch.

Thanks to all who replied.

John Kilheffer
AMP Incorporated

----- Begin Included Message -----

Patch-ID# 100149-03
Keywords: panic mclput mbuf IP packet drops packets
Synopsis: SunOS 4.1 and 4.1.1: system crashes with mclput panic
Date: 07-April-91

SunOS release: 4.1 4.1.1

Topic: kernel panic mclput

BugID's fixed with this patch: 1041559 1053552

Architectures for which this patch is available: sun3 sun3x sun4 sun4c

Problem description:

Bug ID: 1041559
Certain sequence of IP packets cause the mbuf chain to
be corrupted resulting in the above panic.

Bug ID: 1053552
kernels with mclput panic patch installed (ip_input.o)
PatchID 100149-01 will drop IP packets which have any IP
options included in the packet. Problem being incorrect
checksum for packets with IP-header length > 20 bytes

Fix description:

The fix includes patched version of:



as root
the appopriate sun3 sun3x sun4 or sun4c patches as follows:
# mv /sys/sun{3,3x,4,4c}/OBJ/ip_input.o /sys/sun{3,3x,4,4c}/OBJ/ip_input.o.FCS
# cp sun{3,3x,4,4c}/ip_input.o /sys/sun{3,3x,4,4c}/OBJ/ip_input.o
# chmod 444 /sys/sun{3,3x,4,4c}/OBJ/ip_input.o
 A new kernel will need to be configured and built.
 Please refer to the "System and Network Administration" portion
 of the manual for building and installing a custom kernel.


Patch contains 7 files containing 81K bytes

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