linux-kernel - Re: [PATCH v3] platform/chrome: Use proper protocol transfer function

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: Windows password security audit tool. GUI, reports in PDF.

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

Date:   Tue, 19 Sep 2017 23:13:18 -0700
From:   Brian Norris <briannorris@...omium.org>
To:     Shawn N <shawnn@...omium.org>
Cc:     Jon Hunter <jonathanh@...dia.com>, Olof Johansson <olof@...om.net>,
        Benson Leung <bleung@...omium.org>,
        Lee Jones <lee.jones@...aro.org>, linux-kernel@...r.kernel.org,
        Doug Anderson <dianders@...omium.org>,
        Brian Norris <computersforpeace@...il.com>,
        Gwendal Grignou <gwendal@...omium.org>,
        Enric Balletbo <enric.balletbo@...labora.co.uk>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH v3] platform/chrome: Use proper protocol transfer function

Hi,

On Tue, Sep 19, 2017 at 11:05:38PM -0700, Shawn N wrote:
> This is failing because our EC_CMD_GET_PROTOCOL_INFO host command is
> getting messed up, or the reply buffer is getting corrupted somehow.
> 
>                ec_dev->proto_version =
>                         min(EC_HOST_REQUEST_VERSION,
>                                         fls(proto_info->protocol_versions) - 1);
> 
> If proto_info->protocol_versions == 0 then ec_dev->proto_version will
> be assigned 0xffff. The logic here seems strange to me, if the EC is

Whoops...

> successfully replying to our v3 command then obviously it supports v3
> (maybe it will be useful someday if EC_HOST_REQUEST_VERSION is rev'd).
> Anyway, we need to figure out what is happening with our
> EC_HOST_REQUEST_VERSION host command.
> 
> On Tue, Sep 19, 2017 at 10:14 AM, Brian Norris <briannorris@...omium.org> wrote:
> > Hi Jon,
> >
> > On Tue, Sep 19, 2017 at 05:39:56PM +0100, Jon Hunter wrote:
> >> On 19/09/17 15:09, Shawn N wrote:
...
> > Furthermore, the only assignments to this 'proto_version' field look
> > like they're only writing one of 0, 2, 3, or
> >
> >    min(EC_HOST_REQUEST_VERSION, fls(proto_info->protocol_versions) - 1)
> >
> > . I don't see where 0xffff comes from.

...I'm an idiot. While the rvalue (the expression above) is an int (e.g,
-1), it's getting cast into a uint16_t (ec_dev->proto_version). So
that's where the 0xffff can come from.

Sorry if I misled you Shawn :(

Brian