linux-kernel - Re: [PATCH v1] regulator: core: Log forbidden DRMS operation

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: <20190221101238.GB5970@sirena.org.uk>
Date:   Thu, 21 Feb 2019 10:12:38 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Marc Gonzalez <marc.w.gonzalez@...e.fr>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        LKML <linux-kernel@...r.kernel.org>,
        MSM <linux-arm-msm@...r.kernel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Jeffrey Hugo <jhugo@...eaurora.org>,
        Evan Green <evgreen@...omium.org>,
        Douglas Anderson <dianders@...omium.org>
Subject: Re: [PATCH v1] regulator: core: Log forbidden DRMS operation

On Thu, Feb 21, 2019 at 10:42:01AM +0100, Marc Gonzalez wrote:
> On 19/02/2019 17:39, Mark Brown wrote:
> > On Tue, Feb 19, 2019 at 05:02:46PM +0100, Marc Gonzalez wrote:

> > No, it's perfectly normal for machine constraints to stop drivers from
> > doing things so we shouldn't warn on this - it would get incredibly
> > noisy if we started printing every time constraints didn't let us do
> > something at info level.  Debug level might be viable, or definitely
> > vdbg or trace points.

> Several functions return an error (and log a KERN_ERR message) if their
> corresponding flag is not set:
> 
> regulator_check_voltage()	REGULATOR_CHANGE_VOLTAGE

That's a bug due to an incomplete implementation, what it's supposed to
be doing there is checking if the voltage request is satisfied by the
current voltage and returning an error only if the requested voltage is
out of range.

> regulator_check_current_limit()	REGULATOR_CHANGE_CURRENT

This one is less clear than anything else - we might want to error out
here if the device is somehow relying on being able to lower the current
limit for safety.  We'd need an audit of users.

> regulator_mode_constrain()	REGULATOR_CHANGE_MODE

This one is also a bug, modes barely mean anything anyway.

Download attachment "signature.asc" of type "application/pgp-signature" (489 bytes)