From c8e27a4a5136e7230f9e4ffcf132705bf56864cc Mon Sep 17 00:00:00 2001 From: Kent Gibson Date: Wed, 6 Jul 2022 16:45:07 +0800 Subject: gpiolib: cdev: fix null pointer dereference in linereq_free() Fix a kernel NULL pointer dereference reported by gpio kselftests. linereq_free() can be called as part of the cleanup of a failed request, at which time the desc for a line may not have been determined, so it is unsafe to dereference without a check. Add a check prior to dereferencing the line desc. Fixes: 2068339a6c35 ("gpiolib: cdev: Add hardware timestamp clock type") Signed-off-by: Kent Gibson Signed-off-by: Bartosz Golaszewski --- drivers/gpio/gpiolib-cdev.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'drivers/gpio') diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c index f5aa5f93342a..0c9a63becfef 100644 --- a/drivers/gpio/gpiolib-cdev.c +++ b/drivers/gpio/gpiolib-cdev.c @@ -1460,11 +1460,12 @@ static ssize_t linereq_read(struct file *file, static void linereq_free(struct linereq *lr) { unsigned int i; - bool hte; + bool hte = false; for (i = 0; i < lr->num_lines; i++) { - hte = !!test_bit(FLAG_EVENT_CLOCK_HTE, - &lr->lines[i].desc->flags); + if (lr->lines[i].desc) + hte = !!test_bit(FLAG_EVENT_CLOCK_HTE, + &lr->lines[i].desc->flags); edge_detector_stop(&lr->lines[i], hte); if (lr->lines[i].desc) gpiod_free(lr->lines[i].desc); -- cgit v1.2.3