Merge tag 'gpio-v4.7-4' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio

Pull GPIO fixes from Linus Walleij:
 "More GPIO fixes.  Most prominent the gpiod_to_irq() fix brought to my
  attention by Hans de Goede.  The hardening patch is a consequence of
  the reasoning around that bug.

   - It was discovered that too many parts of the kernel does not
     respect gpiod_to_irq() returning zero for an invalid IRQ.  While
     this gets fixed, we need to make it return negative errorcodes
     again.

   - Harden the library a bit when passed error pointers.  It is a bug
     to use these, but let's be helpful and warn the users.

   - Fix an uninitialized spinlock in the 104-idi-48 driver"

* tag 'gpio-v4.7-4' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio:
  gpio: make library immune to error pointers
  gpio: make sure gpiod_to_irq() returns negative on NULL desc
  gpio: 104-idi-48: Fix missing spin_lock_init for ack_lock

2 files changed, 19 insertions, 3 deletions

diff --git a/drivers/gpio/gpio-104-idi-48.c b/drivers/gpio/gpio-104-idi-48.c
index 6c75c83baf5a..2d2763ea1a68 100644
--- a/drivers/gpio/gpio-104-idi-48.c
+++ b/drivers/gpio/gpio-104-idi-48.c
@@ -247,6 +247,7 @@ static int idi_48_probe(struct device *dev, unsigned int id)
         idi48gpio->irq = irq[id];
 
         spin_lock_init(&idi48gpio->lock);
+        spin_lock_init(&idi48gpio->ack_lock);
 
         dev_set_drvdata(dev, idi48gpio);
 
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 58d822d7e8da..570771ed19e6 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1373,8 +1373,12 @@ done:
 #define VALIDATE_DESC(desc) do { \
         if (!desc) \
                 return 0; \
+        if (IS_ERR(desc)) {                                             \
+                pr_warn("%s: invalid GPIO (errorpointer)\n", __func__); \
+                return PTR_ERR(desc); \
+        } \
         if (!desc->gdev) { \
-                pr_warn("%s: invalid GPIO\n", __func__); \
+                pr_warn("%s: invalid GPIO (no device)\n", __func__); \
                 return -EINVAL; \
         } \
         if ( !desc->gdev->chip ) { \
@@ -1386,8 +1390,12 @@ done:
 #define VALIDATE_DESC_VOID(desc) do { \
         if (!desc) \
                 return; \
+        if (IS_ERR(desc)) {                                             \
+                pr_warn("%s: invalid GPIO (errorpointer)\n", __func__); \
+                return; \
+        } \
         if (!desc->gdev) { \
-                pr_warn("%s: invalid GPIO\n", __func__); \
+                pr_warn("%s: invalid GPIO (no device)\n", __func__); \
                 return; \
         } \
         if (!desc->gdev->chip) { \
@@ -2056,7 +2064,14 @@ int gpiod_to_irq(const struct gpio_desc *desc)
         struct gpio_chip *chip;
         int offset;
 
-        VALIDATE_DESC(desc);
+        /*
+         * Cannot VALIDATE_DESC() here as gpiod_to_irq() consumer semantics
+         * requires this function to not return zero on an invalid descriptor
+         * but rather a negative error number.
+         */
+        if (!desc || IS_ERR(desc) || !desc->gdev || !desc->gdev->chip)
+                return -EINVAL;
+
         chip = desc->gdev->chip;
         offset = gpio_chip_hwgpio(desc);
         if (chip->to_irq) {