bugtraq - Re: Hotfix for new mremap vulnerability

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Message-ID: <200402210227.16522@WOLK>
Date: Sat, 21 Feb 2004 04:14:54 +0100
From: Marc-Christian Petersen <m.c.p@....net>
To: bugtraq@...urityfocus.com
Cc: Pavel harry_x Palát <harry_x@...ylon5.cz>
Subject: Re: Hotfix for new mremap vulnerability


On Thursday 19 February 2004 17:32, Pavel harry_x Palát wrote:

Hi Pavel,

> Greetings,
>
> 	Here (http://wizard.ath.cx/fixmremap2.tar.gz) is small hotfix for newly
> discovered mremap() vulnerability. It
> doesn't directly change do_mremap() code, it just overwrites syscall
> handler with LKM. In my opinion it is enough to fix just mremap() syscall
> because at least on x86 there are no other functions which would use
> do_mremap directly. But this may not be true on others platforms (for
> example ia64)...
> The package contains the hotfix and a small proof of concept program which
> can be used to see if kernel is vulnerable.
> Use at your own risk.

- call the POC exploit on a vulnerable system
- echo "1000000" > /proc/sys/vm/max_map_count
- call the POC exploit again
- see the difference

Well, at least it prevents the POC exploit, maybe there's more though.

Kudos to the PaX team :)

-- 
ciao, Marc