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From: riel@redhat.com (Rik van Riel)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 02/11] mm: Hardened usercopy
Date: Thu, 14 Jul 2016 21:04:18 -0400	[thread overview]
Message-ID: <1468544658.30053.26.camel@redhat.com> (raw)
In-Reply-To: <20160714232019.GA28254@350D>

On Fri, 2016-07-15 at 09:20 +1000, Balbir Singh wrote:

> > ==
> > +		???((unsigned long)end & (unsigned
> > long)PAGE_MASK)))
> > +		return NULL;
> > +
> > +	/* Allow if start and end are inside the same compound
> > page. */
> > +	endpage = virt_to_head_page(end);
> > +	if (likely(endpage == page))
> > +		return NULL;
> > +
> > +	/* Allow special areas, device memory, and sometimes
> > kernel data. */
> > +	if (PageReserved(page) && PageReserved(endpage))
> > +		return NULL;
> 
> If we came here, it's likely that endpage > page, do we need to check
> that only the first and last pages are reserved? What about the ones
> in
> the middle?

I think this will be so rare, we can get away with just
checking the beginning and the end.

-- 

All Rights Reversed.
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  reply	other threads:[~2016-07-15  1:04 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-13 21:55 [PATCH v2 0/11] mm: Hardened usercopy Kees Cook
2016-07-13 21:55 ` [PATCH v2 01/11] mm: Implement stack frame object validation Kees Cook
2016-07-13 22:01   ` Andy Lutomirski
2016-07-13 22:04     ` Kees Cook
2016-07-14  5:48       ` Josh Poimboeuf
2016-07-14 18:10         ` Kees Cook
2016-07-14 19:23           ` Josh Poimboeuf
2016-07-14 21:38             ` Kees Cook
2016-07-13 21:55 ` [PATCH v2 02/11] mm: Hardened usercopy Kees Cook
2016-07-14 23:20   ` Balbir Singh
2016-07-15  1:04     ` Rik van Riel [this message]
2016-07-15  1:41       ` Balbir Singh
2016-07-15  4:05         ` Kees Cook
2016-07-15  4:53           ` Kees Cook
2016-07-15 12:55             ` Balbir Singh
2016-07-15  4:25     ` Kees Cook
2016-07-15 19:00       ` [kernel-hardening] " Daniel Micay
2016-07-15 19:14         ` Kees Cook
2016-07-15 19:19           ` Daniel Micay
2016-07-15 19:23             ` Kees Cook
2016-07-13 21:55 ` [PATCH v2 03/11] x86/uaccess: Enable hardened usercopy Kees Cook
2016-07-13 21:55 ` [PATCH v2 04/11] ARM: uaccess: " Kees Cook
2016-07-13 21:55 ` [PATCH v2 05/11] arm64/uaccess: " Kees Cook
2016-07-13 21:55 ` [PATCH v2 06/11] ia64/uaccess: " Kees Cook
2016-07-13 21:56 ` [PATCH v2 07/11] powerpc/uaccess: " Kees Cook
2016-07-13 21:56 ` [PATCH v2 08/11] sparc/uaccess: " Kees Cook
2016-07-13 21:56 ` [PATCH v2 09/11] s390/uaccess: " Kees Cook
2016-07-13 21:56 ` [PATCH v2 10/11] mm: SLAB hardened usercopy support Kees Cook
2016-07-13 21:56 ` [PATCH v2 11/11] mm: SLUB " Kees Cook
2016-07-15  2:05   ` Balbir Singh
2016-07-15  4:29     ` Kees Cook

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