linux-kernel - Re: PROBLEM: NULL pointer dereference in dell_set

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Message-ID: <20180203202243.GA5109@localhost.localdomain>
Date:   Sat, 3 Feb 2018 23:22:43 +0300
From:   Alexander Sergeyev <sergeev917@...il.com>
To:     Mario Limonciello <mario.limonciello@...l.com>,
        Matthew Garrett <mjg59@...f.ucam.org>,
        Pali Rohár <pali.rohar@...il.com>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>
Cc:     platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: PROBLEM: NULL pointer dereference in dell_set_arguments() in 4.15

On Sat, Feb 03, 2018 at 07:20:21PM +0300, Alexander Sergeyev wrote:
> # first bad commit: [549b4930f057658dc50d8010e66219233119a4d8] platform/x86: 
>dell-smbios: Introduce dispatcher for SMM calls

>>From source code (at 549b4930f057) it looks like dell_set_arguments() which
>writes to `buffer` is called before the buffer gets allocated

Turns out that the problem has already surfaced before, but from a different 
origin -- namely, rfkill interface [1]. This was subsequently fixed in 
5246741a3f2e and c6f9288ee460.

This time there is an ordering problem between initialization of the 
dell-laptop module and audio modules which are trying to flash a microphone 
mute led on keyboard (via dell-laptop interface).

And about suspend-to-ram wakeup problem -- is it possible that there was some 
buggy interaction with smbios that led to the observed behaviour?

[1] https://lkml.org/lkml/2017/11/15/705