crashing FreeBSD 5.2.1-RELEASE with tar (!)

Joe Schmoe non_secure at
Sun Jun 20 22:10:17 PDT 2004

FreeBSD 5.2.1-RELEASE is easily crashed with tar.

I have a Intel N440BX single CPU Pentium3, dual fxp0, onboard SCSI.  512M ram, and 256M swap.  NO programs installed or running - just sshd.  I recompiled the kernel, but I _only removed_ raid controllers and ethernet cards that I didn't need (and usb/pccard/firewire/etc.).  Nothing was added to the kernel.  So, all in all a very vanilla, simple, barebones system.

tar up /usr into some other partition - /mnt for instance.  Then untar it there:

tar cvf /mnt/usr.tar /usr; cd /mnt ; tar xvf usr.tar

The untar operation will never complete.  The machine will always crash somewhere during the untar.

In all occassions the crash is such that the machine simply reboots itself and is back up on the network in a few minutes.

It is interesting to note that if I untar usr.tar in a directory in the / partition, the machine survives.  It is only when untarring in another partition that the machine crashes.  ALSO, the deeper you put the tar file in the non-root mount, the less of the tar file gets untarred before the crash.  So if you untar it in /mnt, it gets through a fair amount of the tar file before crashing, but if you untar it in /mnt/test/test/test/test/test/test, it will crash _noticably_ sooner.

What should I do next ?  I cannot stress enough that this is an extremely barebones system, with very very common hardware, and a kernel that has nothing added - just superfluous things removed from it ... and I am crashing it by simply untarring a tar ball (!)


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