Messages in this thread | | | Date | Tue, 9 Aug 2016 18:54:16 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH v2 2/2] x86/KASLR: Increase BRK pages for KASLR memory randomization |
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On Tue, Aug 09, 2016 at 09:35:54AM -0700, Thomas Garnier wrote: > Default implementation expects 6 pages maximum are needed for low page > allocations. If KASLR memory randomization is enabled, the worse case > of e820 layout would require 12 pages (no large pages). It is due to the > PUD level randomization and the variable e820 memory layout. > > This bug was found while doing extensive testing of KASLR memory > randomization on different type of hardware. > > Fixes: 021182e52fe0 ("Enable KASLR for physical mapping memory regions") > Signed-off-by: Thomas Garnier <thgarnie@google.com> > --- > Based on next-20160805 > --- > arch/x86/mm/init.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c > index 6209289..796e7af 100644 > --- a/arch/x86/mm/init.c > +++ b/arch/x86/mm/init.c > @@ -122,8 +122,18 @@ __ref void *alloc_low_pages(unsigned int num) > return __va(pfn << PAGE_SHIFT); > } > > -/* need 3 4k for initial PMD_SIZE, 3 4k for 0-ISA_END_ADDRESS */ > -#define INIT_PGT_BUF_SIZE (6 * PAGE_SIZE) > +/* > + * By default need 3 4k for initial PMD_SIZE, 3 4k for 0-ISA_END_ADDRESS. > + * With KASLR memory randomization, depending on the machine e860 memory layout > + * and the PUD alignement. We may need twice more pages when KASLR memoy > + * randomization is enabled.
Can you please integrate all review feedback before you send your next versions?
There's no "e860" thing and s/memoy/memory/ and s/alignement/alignment/
IOW, just integrate a spellchecker into your workflow.
Thanks.
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --
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