[PATCH] clocksource/drivers: Fix memory leaks in ttc_setup_clockevent and ttc_setup_clocksource

[PATCH] clocksource/drivers: Fix memory leaks in ttc_setup_clockevent and ttc_setup_clocksource

[Navid Emamdoost]

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.

Fixes: 70504f311d4b ("clocksource/drivers/cadence_ttc: Convert init function to return error")
Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.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;
+	}
 
 	ttccs->ttc.base_addr = base;
 	ttccs->cs.name = "ttc_clocksource";
@@ -363,16 +363,20 @@ static int __init ttc_setup_clocksource(struct clk *clk, void __iomem *base,
 		     ttccs->ttc.base_addr + TTC_CNT_CNTRL_OFFSET);
 
 	err = clocksource_register_hz(&ttccs->cs, ttccs->ttc.freq / PRESCALE);
-	if (err) {
-		kfree(ttccs);
-		return err;
-	}
+	if (err)
+		goto release_ttcce;
 
 	ttc_sched_clock_val_reg = base + TTC_COUNT_VAL_OFFSET;
 	sched_clock_register(ttc_sched_clock_read, timer_width,
 			     ttccs->ttc.freq / PRESCALE);
 
 	return 0;
+
+release_ttcce:
+
+	kfree(ttcce);
+	return err;
+
 }
 
 static int ttc_rate_change_clockevent_cb(struct notifier_block *nb,
-- 
2.17.1

Re: [PATCH] clocksource/drivers: Fix memory leaks in ttc_setup_clockevent and ttc_setup_clocksource

[Johan Hovold]

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@gmail.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

Re: [PATCH] clocksource/drivers: Fix memory leaks in ttc_setup_clockevent and ttc_setup_clocksource

[Michal Simek]

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@gmail.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

Re: [PATCH] clocksource/drivers: Fix something in ttc_setup_clockevent and ttc_setup_clocksource

[Markus Elfring]

> In the implementation of ttc_setup_clockevent() and
> ttc_setup_clocksource(), the allocated memory for ttccs is leaked when
> clk_notifier_register() fails.

I suggest to correct your commit message.


> Use goto to direct the execution into error handling path.

* Should the desired completion of the exception handling be described
  by an other wording?

* Will it be better to improve the affected functions by
  separate update steps?

* How do you think about to add the tag “Reported-by” for Michal Simek?
  https://lore.kernel.org/linux-arm-kernel/2a6cdb63-397b-280a-7379-740e8f43ddf6@xilinx.com/


…
> +++ b/drivers/clocksource/timer-cadence-ttc.c
…
> @@ -363,16 +363,20 @@  static int __init ttc_setup_clocksource(struct clk *clk, void __iomem *base,
…
>  	return 0;
> +
> +release_ttcce:
> +
> +	kfree(ttcce);
> +	return err;
…

* Please omit a blank line after the label.

* Is there a need to call the function “clk_disable_unprepare”
  by another jump target?

Regards,
Markus