Messages in this thread | | | From | Thomas Garnier <> | Date | Tue, 9 Aug 2016 10:02:35 -0700 | Subject | Re: [PATCH v2 2/2] x86/KASLR: Increase BRK pages for KASLR memory randomization |
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On Tue, Aug 9, 2016 at 9:54 AM, Borislav Petkov <bp@suse.de> wrote: > 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.
Will do, thanks.
> > 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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