Messages in this thread | | | Date | Fri, 28 Sep 2007 15:52:25 +0100 | From | Ralf Baechle <> | Subject | Re: [PATCH] Break ELF_PLATFORM and stack pointer randomization dependency |
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On Fri, Sep 28, 2007 at 12:59:47PM +0200, Franck Bui-Huu wrote:
> Currently arch_align_stack() is used by fs/binfmt_elf.c to randomize > stack pointer inside a page. But this happens only if ELF_PLATFORM > symbol is defined. > > ELF_PLATFORM is normally set if the architecture wants ld.so to load > implementation specific libraries for optimization. And currently a > lot of architectures just yield this symbol to NULL. > > This is the case for MIPS architecture where ELF_PLATFORM is NULL but > arch_align_stack() has been redefined to do stack inside page > randomization. So in this case no randomization is actually done. > > This patch breaks this dependency which seems to be useless and allows > platforms such MIPS to do the randomization. > > Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com> > --- > > Andrew, > > I tried several times to poke people on the list to understand why > this dependency exists at all, but unfortunately got no answers. > > So I'm submitting this patch to at least have some feedbacks. An > easier solution would be to define ELF_PLATFORM to a dummy string > for MIPS but it sounds very hackish.
Probably this was introduced a long time ago, so it's only recorded in tglx's history git tree:
commit ccc875c1d2fe18b50020d501f1005ef46fc55fed Author: Arjan van de Ven <arjan@infradead.org> Date: Fri Mar 4 17:25:13 2005 -0800
[PATCH] Randomisation: stack randomisation
The patch below replaces the existing 8Kb randomisation of the userspace sta 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 star and once the dust settles we can increase this value to a more agressive value.
Signed-off-by: Arjan van de Ven <arjan@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
http://git.kernel.org/?p=linux/kernel/git/tglx/history.git;a=commitdiff;h=ccc875c1d2fe18b50020d501f1005ef46fc55fed
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