From c8e27a4a5136e7230f9e4ffcf132705bf56864cc Mon Sep 17 00:00:00 2001
From: Kent Gibson <warthog618@gmail.com>
Date: Wed, 6 Jul 2022 16:45:07 +0800
Subject: [PATCH] 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 <warthog618@gmail.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
---
drivers/gpio/gpiolib-cdev.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index f5aa5f93342a4..0c9a63becfef5 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);
--
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