linux-kernel - Re: [PATCH] FDPIC: Ignore the loader's PT_GNU

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Message-ID: <20090704024606.GE1345@ucw.cz>
Date:	Sat, 4 Jul 2009 04:46:07 +0200
From:	Pavel Machek <pavel@....cz>
To:	David Howells <dhowells@...hat.com>
Cc:	vapier.adi@...il.com, rgetz@...ckfin.uclinux.org,
	lethal@...ux-sh.org, gerg@...inux.org,
	uclinux-dist-devel@...ckfin.uclinux.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] FDPIC: Ignore the loader's PT_GNU_STACK when
	calculating the stack size

On Wed 2009-07-01 13:08:14, David Howells wrote:
> Ignore the loader's PT_GNU_STACK when calculating the stack size, and only
> consider the executable's PT_GNU_STACK, assuming the executable has one.
> 
> Currently the behaviour is to take the largest stack size and use that, but
> that means you can't reduce the stack size in the executable.  The loader's
> stack size should probably only be used when executing the loader directly.
> 
> WARNING: This patch is slightly dangerous - it may render a system inoperable
> if the loader's stack size is larger than that of important executables, and
> the system relies unknowingly on this increasing the size of the stack.

The patch seems wrong to me; loader needs the stack, too, right?

What about making sure that the loader specifies reasonable stack
size, instead?

-- 
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