[PATCH 1/2] gpio: cdev: fix missed label sanitizing in debounce_setup()

[Kent Gibson <warthog618@xxxxxxxxx>]

When adding sanitization of the label, the path through
edge_detector_setup() that leads to debounce_setup() was overlooked.
A request taking this path does not allocate a new label and the
request label is freed twice when the request is released, resulting
in memory corruption.

Add label sanitization to debounce_setup().

Cc: stable@xxxxxxxxxxxxxxx
Fixes: b34490879baa ("gpio: cdev: sanitize the label before requesting the interrupt")
Signed-off-by: Kent Gibson <warthog618@xxxxxxxxx>
---
 drivers/gpio/gpiolib-cdev.c | 31 +++++++++++++++++++------------
 1 file changed, 19 insertions(+), 12 deletions(-)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index fa9635610251..f4c2da2041e5 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -728,6 +728,16 @@ static u32 line_event_id(int level)
 		       GPIO_V2_LINE_EVENT_FALLING_EDGE;
 }
 
+static inline char *make_irq_label(const char *orig)
+{
+	return kstrdup_and_replace(orig, '/', ':', GFP_KERNEL);
+}
+
+static inline void free_irq_label(const char *label)
+{
+	kfree(label);
+}
+
 #ifdef CONFIG_HTE
 
 static enum hte_return process_hw_ts_thread(void *p)
@@ -1015,6 +1025,7 @@ static int debounce_setup(struct line *line, unsigned int debounce_period_us)
 {
 	unsigned long irqflags;
 	int ret, level, irq;
+	char *label;
 
 	/* try hardware */
 	ret = gpiod_set_debounce(line->desc, debounce_period_us);
@@ -1037,11 +1048,17 @@ static int debounce_setup(struct line *line, unsigned int debounce_period_us)
 			if (irq < 0)
 				return -ENXIO;
 
+			label = make_irq_label(line->req->label);
+			if (!label)
+				return -ENOMEM;
+
 			irqflags = IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING;
 			ret = request_irq(irq, debounce_irq_handler, irqflags,
-					  line->req->label, line);
-			if (ret)
+					  label, line);
+			if (ret) {
+				free_irq_label(label);
 				return ret;
+			}
 			line->irq = irq;
 		} else {
 			ret = hte_edge_setup(line, GPIO_V2_LINE_FLAG_EDGE_BOTH);
@@ -1083,16 +1100,6 @@ static u32 gpio_v2_line_config_debounce_period(struct gpio_v2_line_config *lc,
 	return 0;
 }
 
-static inline char *make_irq_label(const char *orig)
-{
-	return kstrdup_and_replace(orig, '/', ':', GFP_KERNEL);
-}
-
-static inline void free_irq_label(const char *label)
-{
-	kfree(label);
-}
-
 static void edge_detector_stop(struct line *line)
 {
 	if (line->irq) {
-- 
2.39.2