linux-kernel - Re: [PATCH] clocksource/drivers: Fix memory leaks in ttc_setup_clockevent and ttc_setup

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Date:   Fri, 20 Dec 2019 06:10:13 +0100
From:   Johan Hovold <johan@...nel.org>
To:     Navid Emamdoost <navid.emamdoost@...il.com>
Cc:     Michal Simek <michal.simek@...inx.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Sören Brinkmann <soren.brinkmann@...inx.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        emamd001@....edu
Subject: Re: [PATCH] clocksource/drivers: Fix memory leaks in
 ttc_setup_clockevent and ttc_setup_clocksource

On Thu, Dec 19, 2019 at 06:09:21PM -0600, Navid Emamdoost wrote:
> In the implementation of ttc_setup_clockevent() and
> ttc_setup_clocksource(), the allocated memory for ttccs is leaked when
> clk_notifier_register() fails. Use goto to direct the execution into error
> handling path.

No, that memory was never leaked since that function did not return on
registration errors before your patch.

> Fixes: 70504f311d4b ("clocksource/drivers/cadence_ttc: Convert init function to return error")

Perhaps you meant to fix the actual leak that was added by this commit
in a different function, ttc_setup_clockevent(), when returning on
notifier-registration errors?

Also should the clock be left enabled on errors?

> Signed-off-by: Navid Emamdoost <navid.emamdoost@...il.com>
> ---
>  drivers/clocksource/timer-cadence-ttc.c | 22 +++++++++++++---------
>  1 file changed, 13 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/clocksource/timer-cadence-ttc.c b/drivers/clocksource/timer-cadence-ttc.c
> index c6d11a1cb238..46d69982ad33 100644
> --- a/drivers/clocksource/timer-cadence-ttc.c
> +++ b/drivers/clocksource/timer-cadence-ttc.c
> @@ -328,10 +328,8 @@ static int __init ttc_setup_clocksource(struct clk *clk, void __iomem *base,
>  	ttccs->ttc.clk = clk;
>  
>  	err = clk_prepare_enable(ttccs->ttc.clk);
> -	if (err) {
> -		kfree(ttccs);
> -		return err;
> -	}
> +	if (err)
> +		goto release_ttcce;
>  
>  	ttccs->ttc.freq = clk_get_rate(ttccs->ttc.clk);
>  
> @@ -341,8 +339,10 @@ static int __init ttc_setup_clocksource(struct clk *clk, void __iomem *base,
>  
>  	err = clk_notifier_register(ttccs->ttc.clk,
>  				    &ttccs->ttc.clk_rate_change_nb);
> -	if (err)
> +	if (err) {
>  		pr_warn("Unable to register clock notifier.\n");
> +		goto release_ttcce;
> +	}

Johan