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Groups > linux.kernel > #1292464
| From | Andy Lutomirski <luto@amacapital.net> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: 4.4-rc5: ugly warn on: 5 W+X pages found |
| Date | 2015-12-15 19:50 +0100 |
| Message-ID | <qG2PE-7Xw-19@gated-at.bofh.it> (permalink) |
| References | (6 earlier) <qFIxA-34I-25@gated-at.bofh.it> <qFIQW-3c1-15@gated-at.bofh.it> <qFJN0-3NK-5@gated-at.bofh.it> <qFUp3-2e3-11@gated-at.bofh.it> <qG1TA-7mv-19@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Tue, Dec 15, 2015 at 9:45 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
> On Tue, Dec 15, 2015 at 1:40 AM, Pavel Machek <pavel@ucw.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) &&
> + (protval & _PAGE_RW);
> +}
> +
> /*
> * Mask out unsupported bits in a present pgprot. Non-present pgprots
> * can use those bits for other purposes, so leave them be.
> @@ -345,8 +352,10 @@ static inline pgprotval_t massage_pgprot(pgprot_t pgprot)
> {
> pgprotval_t protval = pgprot_val(pgprot);
>
> - if (protval & _PAGE_PRESENT)
> + if (protval & _PAGE_PRESENT) {
> protval &= __supported_pte_mask;
> + WARN_ON_ONCE(kernel_write_execute_prot(protval));
Shouldn't we switch those two lines? Arguably trying to set rwx
permissions on !PAE is a bug even if it makes no difference, whereas
setting rw- and getting rwx because we don't have NX support on the
platform or kernel build doesn't indicate a bug.
Anyway, I still think that we should apply my patches for 4.5 because
I think they're cleanups, but apparently I guessed wrong as to what
was causing Pavel's issue. But your patch would help diagnose it.
--Andy
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4.4-rc5: ugly warn on: 5 W+X pages found Pavel Machek <pavel@ucw.cz> - 2015-12-14 09:10 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Borislav Petkov <bp@alien8.de> - 2015-12-14 10:00 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Pavel Machek <pavel@ucw.cz> - 2015-12-14 10:10 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Borislav Petkov <bp@alien8.de> - 2015-12-14 10:20 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Linus Torvalds <torvalds@linux-foundation.org> - 2015-12-14 20:20 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Pavel Machek <pavel@ucw.cz> - 2015-12-14 21:30 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Andy Lutomirski <luto@amacapital.net> - 2015-12-14 22:10 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Arjan van de Ven <arjan@linux.intel.com> - 2015-12-14 22:30 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Andy Lutomirski <luto@amacapital.net> - 2015-12-14 23:30 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Pavel Machek <pavel@ucw.cz> - 2015-12-15 10:50 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Linus Torvalds <torvalds@linux-foundation.org> - 2015-12-15 18:50 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Borislav Petkov <bp@alien8.de> - 2015-12-15 19:40 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Linus Torvalds <torvalds@linux-foundation.org> - 2015-12-15 20:10 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Borislav Petkov <bp@alien8.de> - 2015-12-15 20:20 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Andy Lutomirski <luto@amacapital.net> - 2015-12-15 19:50 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Linus Torvalds <torvalds@linux-foundation.org> - 2015-12-15 20:10 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Pavel Machek <pavel@ucw.cz> - 2015-12-15 22:00 +0100
4.4.-rc5: lguest causes ugly warn on: 5 W+X pages found Pavel Machek <pavel@ucw.cz> - 2015-12-15 22:20 +0100
Re: 4.4.-rc5: lguest causes ugly warn on: 5 W+X pages found Rusty Russell <rusty@rustcorp.com.au> - 2015-12-16 03:30 +0100
Re: 4.4.-rc5: lguest causes ugly warn on: 5 W+X pages found Pavel Machek <pavel@ucw.cz> - 2015-12-16 09:20 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Borislav Petkov <bp@alien8.de> - 2015-12-15 22:40 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Pavel Machek <pavel@ucw.cz> - 2015-12-15 23:10 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Borislav Petkov <bp@alien8.de> - 2015-12-15 23:20 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Pavel Machek <pavel@ucw.cz> - 2015-12-15 09:00 +0100
[PATCH 1/2] x86_32/mm: Set NX in __supported_pte_mask before enabling paging Andy Lutomirski <luto@kernel.org> - 2015-12-15 09:10 +0100
[PATCH 2/2] x86/mm: Make kmap_prot into a #define Andy Lutomirski <luto@kernel.org> - 2015-12-15 09:10 +0100
[PATCH 0/2] x86/mm: A _PAGE_NX fixlet and a kmap cleanup Andy Lutomirski <luto@kernel.org> - 2015-12-15 09:10 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Arjan van de Ven <arjan@linux.intel.com> - 2015-12-15 14:40 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Pavel Machek <pavel@ucw.cz> - 2015-12-15 15:10 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found "H. Peter Anvin" <hpa@zytor.com> - 2015-12-15 17:30 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Pavel Machek <pavel@ucw.cz> - 2015-12-15 18:50 +0100
Re: 4.4-rc5: ugly warn on: 5 W+X pages found Pavel Machek <pavel@ucw.cz> - 2015-12-14 13:40 +0100
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