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

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Message-ID: <3d72fe70-25fb-cdee-ac7d-bc1aa2ae5137@xilinx.com>
Date:   Fri, 20 Dec 2019 09:37:44 +0100
From:   Michal Simek <michal.simek@...inx.com>
To:     Johan Hovold <johan@...nel.org>,
        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 20. 12. 19 6:10, Johan Hovold wrote:
> 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;
>> +	}
> 

+ this is IMHO v3 version. It means just label it properly and also keep
changes log.

Thanks,
Michal