linux-kernel - Re: [kernel-hardening] Re: [PATCH v6 03/11] mm, x86: Add support for eXclusive Page Frame Ownership (XPFO)

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Date:   Tue, 14 Nov 2017 16:37:34 -0800
From:   Dave Hansen <dave.hansen@...el.com>
To:     Tycho Andersen <tycho@...ho.ws>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        kernel-hardening@...ts.openwall.com,
        Marco Benatto <marco.antonio.780@...il.com>,
        Juerg Haefliger <juerg.haefliger@...onical.com>, x86@...nel.org
Subject: Re: [kernel-hardening] Re: [PATCH v6 03/11] mm, x86: Add support for
 eXclusive Page Frame Ownership (XPFO)

On 11/14/2017 04:33 PM, Tycho Andersen wrote:
>>
>> void set_bh_page(struct buffer_head *bh,
>> ...
>> 	bh->b_data = page_address(page) + offset;
> Ah, yes. I guess there will be many bugs like this :). Anyway, I'll
> try to cook up a patch.

It won't catch all the bugs, but it might be handy to have a debugging
mode that records the location of the last user of page_address() and
friends.  That way, when we trip over an unmapped page, we have an
easier time finding the offender.