Messages in this thread | | | Date | Mon, 22 May 2006 03:06:07 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH] 2.6.16.16 Parameter-controlled mmap/stack randomization |
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On So 20-05-06 11:23:47, John Richard Moser wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > > > Arjan van de Ven wrote: > > On Fri, 2006-05-19 at 21:00 -0400, John Richard Moser wrote: > >> Any comments on this one? > >> > >> I'm trying to control the stack and heap randomization via command-line > >> parameters. > > > > why? this doesn't really sound like something that needs to be tunable > > to that extend; either it's on or it's off (which is tunable already), > > the exact amount should just be the right value. While I often disagree > > with the gnome desktop guys, they have some point when they say that > > if you can get it right you shouldn't provide a knob. > > This is a "One Size Fits All" argument. > > Oracle breaks with 256M stack/mmap() randomization, so does Linus' mail > client. That's why we have 8M stack and 1M mmap(). > > On the other hand, some things[1][2][3] may give us the undesirable > situation where-- even on an x86-64 with real NX-bit love-- there's an > executable stack. The stack randomization in this case can likely be > weakened by, say, 8 bits by padding your shellcode with 1-byte NOPs > (there's a zillion of these, like inc %eax) up to 4096 bytes. This > leaves 1 success case for every 2047 fail cases.
Maybe we can add more bits of randomness when there's enough address space -- like in x86-64 case? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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