linux-kernel - Re: [PATCH v2] thermal: Fix a NULL pointer dereference

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Message-ID: <ca7eb02d-2b21-9bc0-7abe-2a4e6ab0a07b@linaro.org>
Date:   Wed, 6 Oct 2021 11:39:57 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Subbaraman Narayanamurthy <quic_subbaram@...cinc.com>,
        Zhang Rui <rui.zhang@...el.com>,
        Amit Kucheria <amitk@...nel.org>
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        David Collins <quic_collinsd@...cinc.com>,
        Manaf Meethalavalappu Pallikunhi <manafm@...eaurora.org>,
        Ram Chandrasekar <rkumbako@...eaurora.org>,
        stable@...r.kernel.org
Subject: Re: [PATCH v2] thermal: Fix a NULL pointer dereference

On 06/10/2021 00:09, Subbaraman Narayanamurthy wrote:

[ ... ]

>>> The tests can be replaced by (!data->ops), no ?
>> Thanks Daniel for reviewing the patch.
>>
>> I agree that even if a sensor module is unregistered, that would call
>> "thermal_zone_of_sensor_unregister" which would eventually set NULL on
>> get_temp() and get_trend() and "tzd->ops" as well.
>>
>> However, of_thermal_get_temp() is trying to call "data->ops->get_temp"
>> which comes from a sensor driver when it registers. There is no
>> guarantee that it would be non-NULL right?
>>
>> Thinking of which, I think having both checks would be valid.
> 
> Hi Daniel,
> Do you still have any concerns with this change?

Yes, let me answer to the initial patch.


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