Messages in this thread | | | Date | Tue, 25 Jul 2006 03:46:39 -0400 | From | Chuck Ebbert <> | Subject | [PATCH for 2.6.18rc2] [1/7] i386/x86-64: Don't randomize stack top when... |
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In-Reply-To: <44c514a8.6HlRR82y133O2bd0%ak@suse.de>
On Mon, 24 Jul 2006 20:42:48 +0200, Andi Kleen wrote: > > --- linux.orig/arch/i386/kernel/process.c > +++ linux/arch/i386/kernel/process.c > @@ -37,6 +37,7 @@ > #include <linux/kallsyms.h> > #include <linux/ptrace.h> > #include <linux/random.h> > +#include <linux/personality.h> > > #include <asm/uaccess.h> > #include <asm/pgtable.h> > @@ -905,7 +906,7 @@ asmlinkage int sys_get_thread_area(struc > > unsigned long arch_align_stack(unsigned long sp) > { > - if (randomize_va_space) > + if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) > sp -= get_random_int() % 8192; > return sp & ~0xf; > }
I think this needs to be done always, at least on P4. It really isn't 'randomization' at the same high level as the rest -- more like a small adjustment. And the offset should be a multiple of 128 and < 7K (not 8K.) Something like this:
unsigned int r = get_random_int(); sp &= ~0x7f; sp -= 128 * ((r % 32) + (r / 32 % 16)); return sp;
-- Chuck
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