Messages in this thread |  | | | Subject | Re: Patch 4/6 randomize the stack pointer | | From | Arjan van de Ven <> | | Date | Thu, 27 Jan 2005 21:35:26 +0100 |
On Thu, 2005-01-27 at 20:32 +0000, Christoph Hellwig wrote: > > The patch below replaces the existing 8Kb randomisation of the userspace > > stack pointer (which is currently only done for Hyperthreaded P-IVs) with a > > more general randomisation over a 64Kb range. 64Kb is not a lot, but it's a > > start and once the dust settles we can increase this value to a more > > agressive value. > Why are we doing this for x86 only, btw? > > > +unsigned long arch_align_stack(unsigned long sp) > > +{ > > + if (randomize_va_space) > > + sp -= ((get_random_int() % 4096) << 4); > > + return sp & ~0xf; > > +} > > this looks like it'd work nicely on all architectures.
the problem is that the <<4 is the minimum x86 stack pointer alignment. That value differs per architecture afaics.....
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