linux-kernel - Re: [PATCH v2] platform/chrome: cros_ec

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, 1 Feb 2022 12:17:45 +0000
From:   Alyssa Ross <hi@...ssa.is>
To:     Prashant Malani <pmalani@...omium.org>
Cc:     linux-kernel@...r.kernel.org, Tzung-Bi Shih <tzungbi@...gle.com>,
        Benson Leung <bleung@...omium.org>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Guenter Roeck <groeck@...omium.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        chrome-platform@...ts.linux.dev
Subject: Re: [PATCH v2] platform/chrome: cros_ec_typec: Check for EC device

Hi Prashant,

On Wed, Jan 26, 2022 at 11:08:14PM +0000, Prashant Malani wrote:
> Hi Alyssa,
>
> On Jan 26 23:04, Alyssa Ross wrote:
> > On Wed, Jan 26, 2022 at 07:02:20PM +0000, Prashant Malani wrote:
> > > The Type C ACPI device on older Chromebooks is not generated correctly
> > > (since their EC firmware doesn't support the new commands required). In
> > > such cases, the crafted ACPI device doesn't have an EC parent, and it is
> > > therefore not useful (it shouldn't be generated in the first place since
> > > the EC firmware doesn't support any of the Type C commands).
> > >
> > > To handle devices which use these older firmware revisions, check for
> > > the parent EC device handle, and fail the probe if it's not found.
> > >
> > > Fixes: fdc6b21e2444 ("platform/chrome: Add Type C connector class driver")
> > > Reported-by: Alyssa Ross <hi@...ssa.is>
> > > Reviewed-by: Tzung-Bi Shih <tzungbi@...gle.com>
> > > Signed-off-by: Prashant Malani <pmalani@...omium.org>
> > > ---
> > > Hi Alyssa, could you kindly test this with your existing setup? Thanks!
> >
> > Hi Prashant, I'm happy to test, but I'm on vacation until the end of the
> > week so probably won't get a chance before Monday.
>
> No worries, whenever you get the chance is fine.
>
> >
> > I'm guessing I should be testing with latest upstream coreboot (now that
> > your fix there has been applied)?
>
> You should use the coreboot with which you discovered the crash, so the
> one which *doesn't* contain the fix.

I applied this patch to Linux 5.17-rc2 and tested with the
coreboot_tiano-eve-mrchromebox-20210806.rom firmware.

The Oops has been replaced with
"cros-ec-typec: GOOG0014:00: couldn't find parent EC device".
My laptop now reboots correctly — the hang on reboot is gone.

The cros_ec_typec driver ends up being loaded, but no devices are bound
to it.  This differs from the behaviour with upstream coreboot
(cabf9e33a7), where cros_ec_typec does not end up being loaded.

Assuming all that's the intended behaviour:

Reviewed-by: Alyssa Ross <hi@...ssa.is>
Tested-by: Alyssa Ross <hi@...ssa.is>

BTW: if you need anything else tested on an eve running upstream Linux
and Coreboot in future, I'm happy to be CCed. :)

> Thanks again!
>
> -Prashant

Download attachment "signature.asc" of type "application/pgp-signature" (834 bytes)