oss-security - Re: CVE request: kernel: setup_arg_pages: diagnose excessive argument size

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Date: Fri, 22 Oct 2010 10:33:39 -0400 (EDT)
From: Josh Bressers <bressers@...hat.com>
To: oss-security@...ts.openwall.com
Cc: "Steven M. Christey" <coley@...us.mitre.org>
Subject: Re: CVE request: kernel: setup_arg_pages: diagnose
 excessive argument size

Please use CVE-2010-3858

Thanks.

-- 
    JB


----- "Eugene Teo" <eugene@...hat.com> wrote:

> "The CONFIG_STACK_GROWSDOWN variant of setup_arg_pages() does not
> check 
> the size of the argument/environment area on the stack. When it is 
> unworkably large, shift_arg_pages() hits its BUG_ON. This is
> exploitable 
> with a very large RLIMIT_STACK limit, to create a crash pretty
> easily.
> 
> Check that the initial stack is not too large to make it possible to
> map 
> in any executable.  We're not checking that the actual executable (or
> 
> intepreter, for binfmt_elf) will fit.  So those mappings might clobber
> 
> part of the initial stack mapping.  But that is just userland lossage
> 
> that userland made happen, not a kernel problem."
> 
> Upstream commit:
> http://git.kernel.org/linus/1b528181b2ffa14721fb28ad1bd539fe1732c583
> 
> References:
> http://grsecurity.net/~spender/64bit_dos.c
> https://bugzilla.redhat.com/show_bug.cgi?id=645222
> 
> Eugene
> -- 
> main(i) { putchar(182623909 >> (i-1) * 5&31|!!(i<7)<<6) && main(++i);
> }

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