gpiolib: check the return value of gpio_chip::get_direction()

As per the API contract - gpio_chip::get_direction() may fail and return
a negative error number. However, we treat it as if it always returned 0
or 1. Check the return value of the callback and propagate the error
number up the stack.

Cc: stable@vger.kernel.org
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250210-gpio-sanitize-retvals-v1-1-12ea88506cb2@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index ca2f58a2cd45e7a8f883fd4c326e1e357c51cbb5..29110dc436f15ab578432551270ef574c1144cdb 100644 (file)
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1057,8 +1057,11 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
                desc->gdev = gdev;
 
                if (gc->get_direction && gpiochip_line_is_valid(gc, desc_index)) {
-                       assign_bit(FLAG_IS_OUT,
-                                  &desc->flags, !gc->get_direction(gc, desc_index));
+                       ret = gc->get_direction(gc, desc_index);
+                       if (ret < 0)
+                               goto err_cleanup_desc_srcu;
+
+                       assign_bit(FLAG_IS_OUT, &desc->flags, !ret);
                } else {
                        assign_bit(FLAG_IS_OUT,
                                   &desc->flags, !gc->direction_input);
@@ -2728,13 +2731,18 @@ int gpiod_direction_input_nonotify(struct gpio_desc *desc)
        if (guard.gc->direction_input) {
                ret = guard.gc->direction_input(guard.gc,
                                                gpio_chip_hwgpio(desc));
-       } else if (guard.gc->get_direction &&
-                 (guard.gc->get_direction(guard.gc,
-                                          gpio_chip_hwgpio(desc)) != 1)) {
-               gpiod_warn(desc,
-                          "%s: missing direction_input() operation and line is output\n",
-                          __func__);
-               return -EIO;
+       } else if (guard.gc->get_direction) {
+               ret = guard.gc->get_direction(guard.gc,
+                                             gpio_chip_hwgpio(desc));
+               if (ret < 0)
+                       return ret;
+
+               if (ret != GPIO_LINE_DIRECTION_IN) {
+                       gpiod_warn(desc,
+                                  "%s: missing direction_input() operation and line is output\n",
+                                   __func__);
+                       return -EIO;
+               }
        }
        if (ret == 0) {
                clear_bit(FLAG_IS_OUT, &desc->flags);
@@ -2771,12 +2779,18 @@ static int gpiod_direction_output_raw_commit(struct gpio_desc *desc, int value)
                                                 gpio_chip_hwgpio(desc), val);
        } else {
                /* Check that we are in output mode if we can */
-               if (guard.gc->get_direction &&
-                   guard.gc->get_direction(guard.gc, gpio_chip_hwgpio(desc))) {
-                       gpiod_warn(desc,
-                               "%s: missing direction_output() operation\n",
-                               __func__);
-                       return -EIO;
+               if (guard.gc->get_direction) {
+                       ret = guard.gc->get_direction(guard.gc,
+                                                     gpio_chip_hwgpio(desc));
+                       if (ret < 0)
+                               return ret;
+
+                       if (ret != GPIO_LINE_DIRECTION_OUT) {
+                               gpiod_warn(desc,
+                                          "%s: missing direction_output() operation\n",
+                                          __func__);
+                               return -EIO;
+                       }
                }
                /*
                 * If we can't actively set the direction, we are some