gpio: bail out silently on NULL descriptors

In fdeb8e1547cb9dd39d5d7223b33f3565cf86c28e
("gpio: reflect base and ngpio into gpio_device")
assumed that GPIO descriptors are either valid or error
pointers, but gpiod_get_[index_]optional() actually return
NULL descriptors and then all subsequent calls should just
bail out.

Cc: stable@vger.kernel.org
Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Andrew Lunn <andrew@lunn.ch>
Fixes: fdeb8e1547cb ("gpio: reflect base and ngpio into gpio_device")
Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 8 insertions, 3 deletions

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 68dbff5d8f57..246b6b051b0d 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1367,10 +1367,13 @@ done:
 /*
  * This descriptor validation needs to be inserted verbatim into each
  * function taking a descriptor, so we need to use a preprocessor
- * macro to avoid endless duplication.
+ * macro to avoid endless duplication. If the desc is NULL it is an
+ * optional GPIO and calls should just bail out.
  */
 #define VALIDATE_DESC(desc) do { \
-        if (!desc || !desc->gdev) { \
+        if (!desc) \
+                return 0; \
+        if (!desc->gdev) { \
                 pr_warn("%s: invalid GPIO\n", __func__); \
                 return -EINVAL; \
         } \
@@ -1381,7 +1384,9 @@ done:
         } } while (0)
 
 #define VALIDATE_DESC_VOID(desc) do { \
-        if (!desc || !desc->gdev) { \
+        if (!desc) \
+                return; \
+        if (!desc->gdev) { \
                 pr_warn("%s: invalid GPIO\n", __func__); \
                 return; \
         } \