Merge tag 'gpio-fixes-for-v6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux

Pull gpio fixes from Bartosz Golaszewski:
 "Some last-minute fixes for this release from the GPIO subsystem.

  The first two address a regression in performance reported to me after
  the conversion to using SRCU in GPIOLIB that was merged during the
  v6.9 merge window. The second patch is not technically a fix but since
  after the first one we no longer need to use a per-descriptor SRCU
  struct, I think it's worth to simplify the code before it gets
  released on Sunday.

  The next two commits fix two memory issues: one use-after-free bug and
  one instance of possibly leaking kernel stack memory to user-space.

  Summary:

   - fix a performance regression in GPIO requesting and releasing after
     the conversion to SRCU

   - fix a use-after-free bug due to a race-condition

   - fix leaking stack memory to user-space in a GPIO uABI corner case"

* tag 'gpio-fixes-for-v6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux:
  gpiolib: cdev: fix uninitialised kfifo
  gpiolib: cdev: Fix use after free in lineinfo_changed_notify
  gpiolib: use a single SRCU struct for all GPIO descriptors
  gpiolib: fix the speed of descriptor label setting with SRCU

1 files changed, 16 insertions, 2 deletions

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index d09c7d728365..9dad67ea2597 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -1193,6 +1193,8 @@ static int edge_detector_update(struct line *line,
 				struct gpio_v2_line_config *lc,
 				unsigned int line_idx, u64 edflags)
 {
+	u64 eflags;
+	int ret;
 	u64 active_edflags = READ_ONCE(line->edflags);
 	unsigned int debounce_period_us =
 			gpio_v2_line_config_debounce_period(lc, line_idx);
@@ -1204,6 +1206,18 @@ static int edge_detector_update(struct line *line,
 	/* sw debounced and still will be...*/
 	if (debounce_period_us && READ_ONCE(line->sw_debounced)) {
 		line_set_debounce_period(line, debounce_period_us);
+		/*
+		 * ensure event fifo is initialised if edge detection
+		 * is now enabled.
+		 */
+		eflags = edflags & GPIO_V2_LINE_EDGE_FLAGS;
+		if (eflags && !kfifo_initialized(&line->req->events)) {
+			ret = kfifo_alloc(&line->req->events,
+					  line->req->event_buffer_size,
+					  GFP_KERNEL);
+			if (ret)
+				return ret;
+		}
 		return 0;
 	}
 
@@ -2351,7 +2365,7 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
 
 	dflags = READ_ONCE(desc->flags);
 
-	scoped_guard(srcu, &desc->srcu) {
+	scoped_guard(srcu, &desc->gdev->desc_srcu) {
 		label = gpiod_get_label(desc);
 		if (label && test_bit(FLAG_REQUESTED, &dflags))
 			strscpy(info->consumer, label,
@@ -2799,11 +2813,11 @@ static int gpio_chrdev_release(struct inode *inode, struct file *file)
 	struct gpio_chardev_data *cdev = file->private_data;
 	struct gpio_device *gdev = cdev->gdev;
 
-	bitmap_free(cdev->watched_lines);
 	blocking_notifier_chain_unregister(&gdev->device_notifier,
 					   &cdev->device_unregistered_nb);
 	blocking_notifier_chain_unregister(&gdev->line_state_notifier,
 					   &cdev->lineinfo_changed_nb);
+	bitmap_free(cdev->watched_lines);
 	gpio_device_put(gdev);
 	kfree(cdev);