linux-kernel - Re: [Patch] Elf loader crash while zero-filling .bss

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Message-ID: <Pine.LNX.4.64.0802111944220.7699@twin.jikos.cz>
Date:	Mon, 11 Feb 2008 19:47:22 +0100 (CET)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Abel Bernabeu <abelbg@...rp.com>
cc:	linux-kernel@...r.kernel.org
Subject: Re: [Patch] Elf loader crash while zero-filling .bss

On Mon, 11 Feb 2008, Abel Bernabeu wrote:

> > set_brk(start, end) allocs just page aligned regions (by "colapsing"
> > both extremes to the start of the page in which they lay)... That
> > means than even if both pointers are not equal there are still some
> > chances that set_brk has allocated no space at all because
> > ELF_PAGEALIGN(elf_bss) != ELF_PAGEALIGN(elf_brk).
> Sorry this was an errata in my comment:  no space is allocated at all
> because ELF_PAGEALIGN(elf_bss) == ELF_PAGEALIGN(elf_brk)

I also don't fully understand the "colapsing" part ... ELF_PAGEALIGN() 
really aligns the address to the nearest page boundary at the higher 
address ... so I don't understand the comment about colapsing to the start 
of the page that contains the address, it's seems to me that the real 
behavior is quite the opposite.

-- 
Jiri Kosina
SUSE Labs

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