Re: CFT: Graphics support for /boot/loader

From: Oliver Fromme <olli_at_lurza.secnetix.de>
Date: Fri, 6 Feb 2009 15:13:42 +0100 (CET)
Christian Gusenbauer wrote:
 > Oliver Fromme wrote:
 > > Danny Braniss wrote:
 > > > just tried it via pxe:
 > > > 
 > > > panic: free: guard1 _at_ 0x7f3a4aec from /usr/src/lib/libstand/close.c:79
 > > > 
 > > > what changes are needed in pxeboot?
 > > 
 > > The panic message means that the heap memory was corruped.
 > > It could be caused by a buffer overflow or similar.
 > > I'll try to look into it.
 > 
 > I got this some years ago when I played with FreeBSD 6.1. It has something to 
 > do with reading/parsing the loader.conf file. Inserting some dummy lines 
 > (comments etc.) into loader.conf solves it (at least that's a workaround). As 
 > I've never seen it again since 6.1 I thought it has already been fixed :-(.

I think that's unrelated.  That guard panic just means
that the program has written beyond the memory that was
allocated.

Unfortunately it is difficult to find the piece of code
responsible for that behaviour (especially when I can't
reproduce the problem myself because I don't have a PXE-
capable machine).  It could be almost anywhere.

In fact, the bug doesn't even have to be in the C code:
FORTH supports (and even encourages) pointer arithmetic,
too.  This is real fun ...

Best regards
   Oliver

-- 
Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M.
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"Unix gives you just enough rope to hang yourself --
and then a couple of more feet, just to be sure."
        -- Eric Allman
Received on Fri Feb 06 2009 - 13:13:54 UTC

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