pinctrl: stm32: fix array read out of bound

The existing code does not verify if the "tentative" index exceeds
the size of the array, causing out of bound read.
Issue identified with kasan.

Check the index before using it.

Signed-off-by: Antonio Borneo <antonio.borneo@foss.st.com>
Fixes: 32c170ff15b0 ("pinctrl: stm32: set default gpio line names using pin names")
Link: https://lore.kernel.org/r/20231107110520.4449-1-antonio.borneo@foss.st.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/pinctrl/stm32/pinctrl-stm32.c b/drivers/pinctrl/stm32/pinctrl-stm32.c
index 3a9c458..603f900 100644 (file)
--- a/drivers/pinctrl/stm32/pinctrl-stm32.c
+++ b/drivers/pinctrl/stm32/pinctrl-stm32.c
@@ -1273,9 +1273,11 @@ static struct stm32_desc_pin *stm32_pctrl_get_desc_pin_from_gpio(struct stm32_pi
        int i;
 
        /* With few exceptions (e.g. bank 'Z'), pin number matches with pin index in array */
-       pin_desc = pctl->pins + stm32_pin_nb;
-       if (pin_desc->pin.number == stm32_pin_nb)
-               return pin_desc;
+       if (stm32_pin_nb < pctl->npins) {
+               pin_desc = pctl->pins + stm32_pin_nb;
+               if (pin_desc->pin.number == stm32_pin_nb)
+                       return pin_desc;
+       }
 
        /* Otherwise, loop all array to find the pin with the right number */
        for (i = 0; i < pctl->npins; i++) {