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

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Message-ID: <77f41c67-cd6f-59c5-15b4-c7d8756ca28a@samsung.com>
Date:   Mon, 25 May 2020 14:43:55 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Tomasz Figa <tfiga@...omium.org>,
        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 Tomasz

On 25.05.2020 14:28, Tomasz Figa wrote:
> On Fri, May 22, 2020 at 1:15 PM Marek Szyprowski
> <m.szyprowski@...sung.com> wrote:
>> 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?
Sure, no problem. The fix is trivial.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland