linux-kernel - Re: [PATCH] i2c: core: fix NULL pointer dereference in suspend/resume callbacks

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Date:   Fri, 22 May 2020 16:20:29 +0200
From:   Wolfram Sang <wsa@...-dreams.de>
To:     Marek Szyprowski <m.szyprowski@...sung.com>
Cc:     linux-pm@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Bibby Hsieh <bibby.hsieh@...iatek.com>,
        Tomasz Figa <tfiga@...omium.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        srv_heupstream@...iatek.com,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        linux-samsung-soc@...r.kernel.org
Subject: Re: [PATCH] i2c: core: fix NULL pointer dereference in
 suspend/resume callbacks

On Fri, May 22, 2020 at 01:15:12PM +0200, Marek Szyprowski wrote:
> Hi All,
> 
> On 22.05.2020 12:13, Marek Szyprowski wrote:
> > Commit 6fe12cdbcfe3 ("i2c: core: support bus regulator controlling in
> > adapter") added generic suspend and resume functions for i2c devices.
> > Those functions unconditionally access an i2c_client structure assigned
> > to the given i2c device. However, there exist i2c devices in the system
> > without a valid i2c_client. Add the needed check before accessing the
> > i2c_client.
> 
> Just one more comment. The devices without i2c_client structure are the 
> i2c 'devices' associated with the respective i2c bus. They are visible 
> in /sys:
> 
> ls -l /sys/bus/i2c/devices/i2c-*
> 
> I wonder if this patch has been ever tested with system suspend/resume, 
> as those devices are always available in the system...

There was another issue with this patch. Although it is not clear yet,
if the patch itself is the culprit or if it just unshadows something
else, however, I am considering to just revert it until these issues are
fixed.


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