gpio: cdev: check for NULL labels when sanitizing them for irqs

commit b3b95964590a3d756d69ea8604c856de805479ad upstream.

We need to take into account that a line's consumer label may be NULL
and not try to kstrdup() it in that case but rather pass the NULL
pointer up the stack to the interrupt request function.

To that end: let make_irq_label() return NULL as a valid return value
and use ERR_PTR() instead to signal an allocation failure to callers.

Cc: stable@vger.kernel.org
Fixes: b34490879baa ("gpio: cdev: sanitize the label before requesting the interrupt")
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Closes: https://lore.kernel.org/lkml/20240402093534.212283-1-naresh.kamboju@linaro.org/
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 053ce7c000f6223c8b49ca62244f73c97de70055..937752d5eb2eabf8adc50c0ac835836bd5fbf1e4 100644 (file)
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -1012,7 +1012,16 @@ static u32 gpio_v2_line_config_debounce_period(struct gpio_v2_line_config *lc,
 
 static inline char *make_irq_label(const char *orig)
 {
-       return kstrdup_and_replace(orig, '/', ':', GFP_KERNEL);
+       char *new;
+
+       if (!orig)
+               return NULL;
+
+       new = kstrdup_and_replace(orig, '/', ':', GFP_KERNEL);
+       if (!new)
+               return ERR_PTR(-ENOMEM);
+
+       return new;
 }
 
 static inline void free_irq_label(const char *label)
@@ -1086,8 +1095,8 @@ static int edge_detector_setup(struct line *line,
        irqflags |= IRQF_ONESHOT;
 
        label = make_irq_label(line->req->label);
-       if (!label)
-               return -ENOMEM;
+       if (IS_ERR(label))
+               return PTR_ERR(label);
 
        /* Request a thread to read the events */
        ret = request_threaded_irq(irq, edge_irq_handler, edge_irq_thread,
@@ -2194,8 +2203,8 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
                goto out_free_le;
 
        label = make_irq_label(le->label);
-       if (!label) {
-               ret = -ENOMEM;
+       if (IS_ERR(label)) {
+               ret = PTR_ERR(label);
                goto out_free_le;
        }