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

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Message-ID: <47B0B1AB.3020203@zytor.com>
Date:	Mon, 11 Feb 2008 12:35:55 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Jiri Kosina <jkosina@...e.cz>
CC:	Abel Bernabeu <abelbg@...rp.com>, linux-kernel@...r.kernel.org
Subject: Re: [Patch] Elf loader crash while zero-filling .bss

Jiri Kosina wrote:
> On Mon, 11 Feb 2008, Abel Bernabeu wrote:
> 
>> In such a way that set_brk(0x0, 0x100) does not alloc any space at all. 
>> There are just more ways to get no memory allocation than 
>> set_brk(elf_bss, elf_bss) (the equalness condition i've changed).
>> Sorry, the correct description for the patch may be:
>> set_brk(start, end) allocs just page aligned regions (by "colapsing"
>> both extremes to the END 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 because
>> ELF_PAGEALIGN(elf_bss) == ELF_PAGEALIGN(elf_brk)
> 
> Now, the question is whether it is valid for ELF binary to not have the 
> end of .bss section (if present at all) not page-aligned.
> 

Why wouldn't it be?  It would, however, be valid to the kernel to round 
it up to the next boundary.

	-hpa
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