From 1f4a640e9ac7f450752365541ad9c064b13ef8bf Mon Sep 17 00:00:00 2001 From: Bartosz Golaszewski Date: Thu, 24 Oct 2024 15:38:34 +0200 Subject: [PATCH] gpiolib: fix a NULL-pointer dereference when setting direction For optional GPIOs we may pass NULL to gpiod_direction_(input|output)(). With the call to the notifier chain added by commit 07c61d4da43f ("gpiolib: notify user-space about in-kernel line state changes") we will now dereference a NULL pointer in this case. The reason for that is the fact that the expansion of the VALIDATE_DESC() macro (which returns 0 for NULL descriptors) was moved into the nonotify variants of the direction setters. Move them back to the top-level interfaces as the nonotify ones are only ever called from inside the GPIO core and are always passed valid GPIO descriptors. This way we'll never call the line_state notifier chain with non-valid descs. Fixes: 07c61d4da43f ("gpiolib: notify user-space about in-kernel line state changes") Reported-by: Mark Brown Closes: https://lore.kernel.org/all/d6601a31-7685-4b21-9271-1b76116cc483@sirena.org.uk/ Tested-by: Klara Modin Tested-by: Mark Brown Link: https://lore.kernel.org/r/20241024133834.47395-1-brgl@bgdev.pl Signed-off-by: Bartosz Golaszewski --- drivers/gpio/gpiolib.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index ae758ba6dc3d..6001ec96693c 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -2695,6 +2695,8 @@ int gpiod_direction_input(struct gpio_desc *desc) { int ret; + VALIDATE_DESC(desc); + ret = gpiod_direction_input_nonotify(desc); if (ret == 0) gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_CONFIG); @@ -2707,8 +2709,6 @@ int gpiod_direction_input_nonotify(struct gpio_desc *desc) { int ret = 0; - VALIDATE_DESC(desc); - CLASS(gpio_chip_guard, guard)(desc); if (!guard.gc) return -ENODEV; @@ -2841,6 +2841,8 @@ int gpiod_direction_output(struct gpio_desc *desc, int value) { int ret; + VALIDATE_DESC(desc); + ret = gpiod_direction_output_nonotify(desc, value); if (ret == 0) gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_CONFIG); @@ -2854,8 +2856,6 @@ int gpiod_direction_output_nonotify(struct gpio_desc *desc, int value) unsigned long flags; int ret; - VALIDATE_DESC(desc); - flags = READ_ONCE(desc->flags); if (test_bit(FLAG_ACTIVE_LOW, &flags)) -- 2.25.1