linux-kernel - Re: [PATCH v2] clk: Fix memory leak in devm_clk_notifier

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Message-ID: <35f6212e-69f8-432f-a5c8-99ed5c844f11@moroto.mountain>
Date:   Mon, 19 Jun 2023 11:48:36 +0300
From:   Dan Carpenter <dan.carpenter@...aro.org>
To:     Fei Shao <fshao@...omium.org>
Cc:     Stephen Boyd <sboyd@...nel.org>,
        Jerome Brunet <jbrunet@...libre.com>,
        Michael Turquette <mturquette@...libre.com>,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] clk: Fix memory leak in devm_clk_notifier_register()

On Mon, Jun 19, 2023 at 11:22:53AM +0800, Fei Shao wrote:
> devm_clk_notifier_register() allocates a devres resource for clk
> notifier but didn't register that to the device, so the notifier didn't
> get unregistered on device detach and the allocated resource was leaked.
> 
> Fix the issue by registering the resource through devres_add().
> 
> Fixes: 6d30d50d037d ("clk: add devm variant of clk_notifier_register")
> Signed-off-by: Fei Shao <fshao@...omium.org>
> ---
> 

Reviewed-by: Dan Carpenter <dan.carpenter@...aro.org>

How did you find this bug?

I can think of some ways to find this bug with static analysis.

KTODO: static analysis:  look at unused parameters

Both GCC and Clang have a warning for unused parameters.  I think the
last time I looked at GCC it had a lot of false positives for functions
which were called as pointers but hopefully that has been fixed now?
Smatch does not have a check for this.  If someone were to write it,
I would probably the check under the --pedantic flag so it would be
turned off by default.

regards,
dan carpenter