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

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Message-ID: <CAAFQd5DdiKDGsodJF_KW8H6YYwAkeaJLE7CoJ=cEX5KeTzO5mw@mail.gmail.com>
Date:   Mon, 25 May 2020 14:28:36 +0200
From:   Tomasz Figa <tfiga@...omium.org>
To:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Bibby Hsieh <bibby.hsieh@...iatek.com>
Cc:     Linux PM <linux-pm@...r.kernel.org>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        srv_heupstream <srv_heupstream@...iatek.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        linux-samsung-soc <linux-samsung-soc@...r.kernel.org>
Subject: Re: [PATCH] i2c: core: fix NULL pointer dereference in suspend/resume callbacks

Hi Marek,

On Fri, May 22, 2020 at 1:15 PM Marek Szyprowski
<m.szyprowski@...sung.com> 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...

Sorry for the trouble and thanks a lot for the fix. We'll make sure to
do more thorough testing, including suspend/resume before relanding
this change.

Since the patch was reverted, can we squash your fix with the next
revision together with your Co-developed-by and Signed-off-by tags?

Best regards,
Tomasz