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Date: Tue, 15 Dec 2015 19:30:05 +0100 From: Borislav Petkov <bp@...en8.de> To: Linus Torvalds <torvalds@...ux-foundation.org> Cc: Pavel Machek <pavel@....cz>, Andy Lutomirski <luto@...capital.net>, Arjan van de Ven <arjan@...ux.intel.com>, kernel list <linux-kernel@...r.kernel.org>, Stephen Smalley <sds@...ho.nsa.gov>, Brian Gerst <brgerst@...il.com>, Denys Vlasenko <dvlasenk@...hat.com>, Peter Anvin <hpa@...or.com>, Mike Galbraith <efault@....de>, Peter Zijlstra <peterz@...radead.org>, Thomas Gleixner <tglx@...utronix.de> Subject: Re: 4.4-rc5: ugly warn on: 5 W+X pages found On Tue, Dec 15, 2015 at 09:45:40AM -0800, Linus Torvalds wrote: > On Tue, Dec 15, 2015 at 1:40 AM, Pavel Machek <pavel@....cz> wrote: > > > > I tried applying: > > > > [PATCH 1/2] x86_32/mm: Set NX in __supported_pte_mask before enabling > > paging > > > > but I still get > > > > [ 2.691897] x86/mm: Found insecure W+X mapping at address ffe69000/0xffe69000 > > This may be an insane suggestion, but how about we try to detect when > that entry gets set, rather than after the fact. > > Something really brute-force like > > diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h > index 6ec0c8b2e9df..538c9bb239b9 100644 > --- a/arch/x86/include/asm/pgtable.h > +++ b/arch/x86/include/asm/pgtable.h > @@ -337,6 +337,13 @@ static inline pmd_t pmd_clear_soft_dirty(pmd_t pmd) > > #endif /* CONFIG_HAVE_ARCH_SOFT_DIRTY */ > > +static inline int kernel_write_execute_prot(pgprotval_t protval) > +{ > + return !(protval & _PAGE_USER) && > + !(protval & _PAGE_NX) && Shouldn't this be without a "!"? AFAIU, we want _PAGE_NX | _PAGE_RW? -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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