linux-kernel - Re: [PATCHv2 2/2] mm/page_poisoning.c: Allow for zero poisoning

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Message-ID: <2210767.i4rORgf7qQ@vostro.rjw.lan>
Date:	Fri, 29 Jan 2016 04:55:44 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Laura Abbott <labbott@...oraproject.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Michal Hocko <mhocko@...e.com>, Pavel Machek <pavel@....cz>,
	Len Brown <len.brown@...el.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com,
	Kees Cook <keescook@...omium.org>, linux-pm@...r.kernel.org
Subject: Re: [PATCHv2 2/2] mm/page_poisoning.c: Allow for zero poisoning

On Thursday, January 28, 2016 06:38:19 PM Laura Abbott wrote:
> By default, page poisoning uses a poison value (0xaa) on free. If this
> is changed to 0, the page is not only sanitized but zeroing on alloc
> with __GFP_ZERO can be skipped as well. The tradeoff is that detecting
> corruption from the poisoning is harder to detect. This feature also
> cannot be used with hibernation since pages are not guaranteed to be
> zeroed after hibernation.
> 
> Credit to Grsecurity/PaX team for inspiring this work
> 
> Signed-off-by: Laura Abbott <labbott@...oraproject.org>

The hibernation disabling part is fine by me.

Please feel free to add an ACK from me to this if that helps.

Thanks,
Rafael