linux-kernel - Re: [PATCH] ion: scatterlist offset not used for buffer map

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20160408065626.GA25580@e106921-lin.trondheim.arm.com>
Date:	Fri, 8 Apr 2016 08:56:27 +0200
From:	John Einar Reitan <john.reitan@...s.arm.com>
To:	Laura Abbott <labbott@...hat.com>
Cc:	gregkh@...uxfoundation.org, arve@...roid.com,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ion: scatterlist offset not used for buffer map

On Thu, Apr 07, 2016 at 12:37:50PM -0700, Laura Abbott wrote:
> On 04/07/2016 04:29 AM, John Einar Reitan wrote:
> > ion's default user/kernel page mapping code don't honor the offset
> > option for scatterlists. It uses sg_page and expect the whole page to be
> > mapped, while the offset could dictate an offset within a large page.
> >
> > sg_phys correctly accounts for the offset, so should be used instead.
> >
> 
> Can you be more specific about which heap and which allocation pattern
> is exposing this bug?

The heap that exposed the bug is one I'm developing and will be posting
as a RFC soon. It uses compound pages and an sub-divides it into surface
buffers. The ion buffers are configured to hold sgl's with the compound
page and the correct offset of the buffer, via 
sg_set_page(.., compound_page, .., offset_of_logical_buffer);

sg_phys/sg_virt  includes this offset, but if you poke the sg and extract
the page with sg_page yourself you must include this offset in your
calculations too.