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Date: Tue, 8 Apr 2008 11:39:22 -0700
From: "Yinghai Lu" <yhlu.kernel@gmail.com>
To: "Alexander van Heukelum" <heukelum@mailshack.com>,
       "Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [PATCH] x86: cleanup boot-heap usage
Cc: "Ingo Molnar" <mingo@elte.hu>, "H. Peter Anvin" <hpa@zytor.com>,
       "Mike Travis" <travis@sgi.com>, "Thomas Gleixner" <tglx@linutronix.de>,
       "Andrew Morton" <akpm@linux-foundation.org>,
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On Tue, Apr 8, 2008 at 3:54 AM, Alexander van Heukelum
<heukelum@mailshack.com> wrote:
> The kernel decompressor wrapper uses memory located beyond the
>  end of the image. This might lead to hard to debug problems,
>  but even if it can be proven to be safe, it is at the very
>  least unclean. I don't see any advantages either, unless you
>  count it not being zeroed out as an advantage. This patch
>  moves the boot-heap area to the bss segment.
>
>  Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
>
>  ---
>
>  On Tue, Apr 08, 2008 at 10:23:54AM +0200, Ingo Molnar wrote:
>  > * Alexander van Heukelum <heukelum@mailshack.com> wrote:
>  > > I did see that the malloc space that the inflate code is using is
>  > > taken from _after_ the end of the bss. I don't see how this is
>  > > protected from being used/overwritten. Changing the stack size changes
>  > > the memory layout a bit... maybe you were so unlucky to create a
>  > > vmlinux image that was just barely smaller than some threshold and
>  > > increasing the stack size made the decompression/relocation area be
>  > > located somewhere else?
the compressed image is copied to end of buff ( with extra code size
for from relocated: in .text to _end)
and do the on possition decompressed. .text section is near end.

YH