Re: How to enable/disable security features on mmap() ?

[linux-os (Dick Johnson)]

On Thu, 8 Dec 2005, Emmanuel Fleury wrote:

> Arjan van de Ven wrote:
>>
>> well it's a /proc/ variable already! So you can just turn it off
>> entirely at runtime. (what is better is that you use the setarch program
>> to turn it off for selected programs though...)
>
> I knew it was a stupid question ! I fooled myself once more ! ;-)
> I'll take a look at this familly of variables and at the proc entries.
>
> Thanks a lot !
> --
> Emmanuel Fleury

In reference to the random-stack patch....

Executing the following program on linux-2.6.13.4:

#include <stdio.h>

int main()
{
     int foo;
     printf("%p\n", &foo);
     return 0;
}

... a few thousand times and sorting its output shows
the stack varies from:
 	0xbf7fe144 -> 0xbffff674

Isn't this too much?  I thought the random-stack patch was
only supposed to vary it a page or 64k at most. This looks
like some broken logic because it varies almost 8 megabytes!
No wonder some of my user's database programs sometimes seg-fault
and other times work perfectly fine. I think this is incorrect
and shows a serious bug (misbehavior).

Cheers,
Dick Johnson
Penguin : Linux version 2.6.13.4 on an i686 machine (5589.55 BogoMips).
Warning : 98.36% of all statistics are fiction.
.

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