Re: [PATCH] gpio: cdev: check for NULL labels when sanitizing them for irqs

[Anders Roxell <anders.roxell@xxxxxxxxxx>]

On Tue, 2 Apr 2024 at 13:42, Bartosz Golaszewski <brgl@xxxxxxxx> wrote:
>
> From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
>
> 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@xxxxxxxxxxxxxxx
> Fixes: b34490879baa ("gpio: cdev: sanitize the label before requesting the interrupt")
> Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>
> Closes: https://lore.kernel.org/lkml/20240402093534.212283-1-naresh.kamboju@xxxxxxxxxx/
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>

Tested-by: Anders Roxell <anders.roxell@xxxxxxxxxx>

Thank you for the quick fix Bartosz,
I applied this patch ontop of linux-next, tag next-20240402. the
libgpiod testsuite passed.

Cheers,
Anders

> ---
>  drivers/gpio/gpiolib-cdev.c | 19 ++++++++++++++-----
>  1 file changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
> index fa9635610251..1426cc1c4a28 100644
> --- a/drivers/gpio/gpiolib-cdev.c
> +++ b/drivers/gpio/gpiolib-cdev.c
> @@ -1085,7 +1085,16 @@ 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)
> @@ -1158,8 +1167,8 @@ 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,
> @@ -2217,8 +2226,8 @@ 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;
>         }
>
> --
> 2.40.1
>