[PATCH] clocksource: timer-cadence-ttc: Fix resource leaks in error paths

[PATCH] clocksource: timer-cadence-ttc: Fix resource leaks in error paths

[Haotian Zhang]

The ttc_setup_clocksource() and ttc_setup_clockevent() fail to
unregister the clock notifier in their error paths, potentially
leading to a resource leak. Additionally, ttc_setup_clocksource()
leaks the prepared clock reference upon failure.

Unregister the clock notifier and disable the clock in the
error path of ttc_setup_clocksource(). Also, add the missing
clock notifier unregistration in the error path of
ttc_setup_clockevent() to ensure proper cleanup.

Fixes: e932900a3279 ("arm: zynq: Use standard timer binding")
Fixes: 91dc985c5e51 ("ARM: zynq: add clk binding support to the ttc")
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
---
 drivers/clocksource/timer-cadence-ttc.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/clocksource/timer-cadence-ttc.c b/drivers/clocksource/timer-cadence-ttc.c
index b8a1cf59b9d6..70384faad66d 100644
--- a/drivers/clocksource/timer-cadence-ttc.c
+++ b/drivers/clocksource/timer-cadence-ttc.c
@@ -333,6 +333,7 @@ static int __init ttc_setup_clocksource(struct clk *clk, void __iomem *base,
 {
 	struct ttc_timer_clocksource *ttccs;
 	int err;
+	bool notifier_registered = false;
 
 	ttccs = kzalloc(sizeof(*ttccs), GFP_KERNEL);
 	if (!ttccs)
@@ -356,6 +357,8 @@ static int __init ttc_setup_clocksource(struct clk *clk, void __iomem *base,
 				    &ttccs->ttc.clk_rate_change_nb);
 	if (err)
 		pr_warn("Unable to register clock notifier.\n");
+	else
+		notifier_registered = true;
 
 	ttccs->ttc.base_addr = base;
 	ttccs->cs.name = "ttc_clocksource";
@@ -377,6 +380,10 @@ static int __init ttc_setup_clocksource(struct clk *clk, void __iomem *base,
 
 	err = clocksource_register_hz(&ttccs->cs, ttccs->ttc.freq / PRESCALE);
 	if (err) {
+		if (notifier_registered)
+			clk_notifier_unregister(ttccs->ttc.clk,
+					&ttccs->ttc.clk_rate_change_nb);
+		clk_disable_unprepare(ttccs->ttc.clk);
 		kfree(ttccs);
 		return err;
 	}
@@ -465,13 +472,16 @@ static int __init ttc_setup_clockevent(struct clk *clk,
 	err = request_irq(irq, ttc_clock_event_interrupt,
 			  IRQF_TIMER, ttcce->ce.name, ttcce);
 	if (err)
-		goto out_clk_unprepare;
+		goto out_clk_notifier_unregister;
 
 	clockevents_config_and_register(&ttcce->ce,
 			ttcce->ttc.freq / PRESCALE, 1, 0xfffe);
 
 	return 0;
 
+out_clk_notifier_unregister:
+	clk_notifier_unregister(ttcce->ttc.clk,
+			&ttcce->ttc.clk_rate_change_nb);
 out_clk_unprepare:
 	clk_disable_unprepare(ttcce->ttc.clk);
 out_kfree:
-- 
2.50.1.windows.1

Re: [PATCH] clocksource: timer-cadence-ttc: Fix resource leaks in error paths

[Markus Elfring]

> The ttc_setup_clocksource() and ttc_setup_clockevent() fail to
> unregister the clock notifier in their error paths, potentially
> leading to a resource leak. Additionally, ttc_setup_clocksource()
> leaks the prepared clock reference upon failure.
…

You may occasionally put more than 65 characters into text lines
of such a change description.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.18-rc7#n658


…
> +++ b/drivers/clocksource/timer-cadence-ttc.c
…
> @@ -377,6 +380,10 @@ static int __init ttc_setup_clocksource(struct clk *clk, void __iomem *base,
>  
>  	err = clocksource_register_hz(&ttccs->cs, ttccs->ttc.freq / PRESCALE);
>  	if (err) {
> +		if (notifier_registered)
> +			clk_notifier_unregister(ttccs->ttc.clk,
> +					&ttccs->ttc.clk_rate_change_nb);
> +		clk_disable_unprepare(ttccs->ttc.clk);
>  		kfree(ttccs);
>  		return err;
>  	}

How do you think about to avoid repeated kfree() calls in such a function implementation?


> @@ -465,13 +472,16 @@ static int __init ttc_setup_clockevent(struct clk *clk,
…
> +out_clk_notifier_unregister:
> +	clk_notifier_unregister(ttcce->ttc.clk,
> +			&ttcce->ttc.clk_rate_change_nb);
…

You may specify this function call in a single line.

Regards,
Markus