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Date:      Thu, 7 Jan 1999 02:07:47 +0000 (GMT)
From:      Terry Lambert <tlambert@primenet.com>
To:        csg@physics.purdue.edu (C. Stephen Gunn)
Cc:        freebsd-hackers@FreeBSD.ORG, ajk@physics.purdue.edu, crh@physics.purdue.edu, jonsmith@physics.purdue.edu, bp@physics.purdue.edu, ab@eas.purdue.edu
Subject:   Re: NFS problems under 3.0-RELEASE
Message-ID:  <199901070207.TAA07487@usr09.primenet.com>
In-Reply-To: <199901062142.QAA13257@galileo.physics.purdue.edu> from "C. Stephen Gunn" at Jan 6, 99 04:41:57 pm

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> This still doesn't address the problem though.  Someone is smashing
> this vnode pointer, usually with 0x0100, as far as I can tell.
> I've not had the time to digest all of the nfs/vfs changes that
> have happened since 3.0 release, but the CVS logs didn't seem to
> indicate changes that might address this.

Dump from 32 bytes before the problem to 64 bytes after as hex.

See if the corruption, in fact, contains the ethernet address of one
or both machines.

If it does, then what's happening is that a stack address is being
used for a structure that's modified later, but the code that gave
the address has already returned, somewhere in your kernel.

The last place this bug occurred was in the IPFW "reject" response,
where the packet was on the stack, queued for send, and then the
code doing the queing returned.  This resulted in  random kernel
stack corruption later on in whatever process was in the kernel
providing the stack at the time the network interrupt occurred.

I suspect there's a number of places in NFS where stack variables
are used, but a buffer should have been allocated instead (and later
freed by whoever was given the buffer to process).


					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.

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