linux-kernel - Re: Executability of the stack

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Message-ID: <45814544.1050102@superbug.co.uk>
Date:	Thu, 14 Dec 2006 12:36:20 +0000
From:	James Courtier-Dutton <James@...erbug.co.uk>
To:	Arjan van de Ven <arjan@...radead.org>
CC:	Franck Pommereau <pommereau@...v-paris12.fr>,
	linux-kernel@...r.kernel.org
Subject: Re: Executability of the stack

Arjan van de Ven wrote:
> On Thu, 2006-12-14 at 10:26 +0100, Franck Pommereau wrote:
>> Dear Linux developers,
>>
>> I recently discovered that the Linux kernel on 32 bits x86 processors
>> reports the stack as being non-executable while it is actually
>> executable (because located in the same memory segment).
> 
> this is not per se true, it depends on the capabilities of your 32 bit
> x86 processor.
> 
> 
>> # grep maps /proc/self/maps
>> bfce8000-bfcfe000 rw-p bfce8000 00:00 0          [stack]
> 
> this shows that the *intent* is to have it non-executable. 
> Not all x86 processors can enforce this. All modern ones do.
> 
>> Is there any reason for this situation? 
> 
> the alternative (showing effective permission) is equally confusing;
> apps would see permissions they didn't set...
> 

Why not show both.
"intent" and "effective".

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