Help Request - Fix Out of Bounds Subscript Warning in Raspberry Pi

[Joel Sherrill]

Pavel,

Feel free to commit the patch.

Why do you think the warning is a false positive?

--joel

On Tue, Apr 25, 2017 at 4:53 AM, Pavel Pisa <ppisa4lists at pikron.com> wrote:

> From 3a2957faeb744af08196f1fd3baac71f15d76c85 Mon Sep 17 00:00:00 2001
> Message-Id: <3a2957faeb744af08196f1fd3baac71f15d76c85.1493113587.git.
> ppisa at pikron.com>
> From: Pavel Pisa <ppisa at pikron.com>
> Date: Tue, 25 Apr 2017 11:45:57 +0200
> Subject: [PATCH] bsp/raspberrypi: GPIO silence warning and ensure that
> lock is
>  always released.
> To: rtems-devel at rtems.org
>
> Signed-off-by: Pavel Pisa <ppisa at pikron.com>
> ---
>  c/src/lib/libbsp/shared/gpio.c | 18 ++++++++++++------
>  1 file changed, 12 insertions(+), 6 deletions(-)
>
> Not tested or even compiled quick fix of warning and more serious real
> problem.
> The waning seems to be GCC false positive. The first iteration
> (i == 0) sets *bank_number for sure. But return with RTEMS_INVALID_ID can
> happen without lock release.
>
> diff --git a/c/src/lib/libbsp/shared/gpio.c b/c/src/lib/libbsp/shared/
> gpio.c
> index 9ceeb407..bf0e415 100644
> --- a/c/src/lib/libbsp/shared/gpio.c
> +++ b/c/src/lib/libbsp/shared/gpio.c
> @@ -303,6 +303,7 @@ static rtems_status_code get_pin_bitmask(
>    uint32_t pin_number;
>    uint32_t bank;
>    uint8_t i;
> +  int locked_bank = -1;
>
>    if ( pin_count < 1 ) {
>      return RTEMS_UNSATISFIED;
> @@ -314,18 +315,23 @@ static rtems_status_code get_pin_bitmask(
>      pin_number = pins[i];
>
>      if ( pin_number < 0 || pin_number >= BSP_GPIO_PIN_COUNT ) {
> +      if (locked_bank >= 0)
> +        RELEASE_LOCK(gpio_bank_state[locked_bank].lock);
> +
>        return RTEMS_INVALID_ID;
>      }
>
>      bank = BANK_NUMBER(pin_number);
>
> -    if ( i == 0 ) {
> +    if ( locked_bank < 0 ) {
>        *bank_number = bank;
> +      locked_bank = bank;
>
> -      ACQUIRE_LOCK(gpio_bank_state[bank].lock);
> +      ACQUIRE_LOCK(gpio_bank_state[locked_bank].lock);
>      }
> -    else if ( bank != *bank_number ) {
> -      RELEASE_LOCK(gpio_bank_state[*bank_number].lock);
> +    else if ( bank != locked_bank ) {
> +      if (locked_bank >= 0)
> +        RELEASE_LOCK(gpio_bank_state[locked_bank].lock);
>
>        return RTEMS_UNSATISFIED;
>      }
> @@ -334,7 +340,7 @@ static rtems_status_code get_pin_bitmask(
>          gpio_pin_state[pin_number].pin_function != function ||
>          gpio_pin_state[pin_number].on_group
>      ) {
> -      RELEASE_LOCK(gpio_bank_state[bank].lock);
> +      RELEASE_LOCK(gpio_bank_state[locked_bank].lock);
>
>        return RTEMS_NOT_CONFIGURED;
>      }
> @@ -342,7 +348,7 @@ static rtems_status_code get_pin_bitmask(
>      *bitmask |= (1 << PIN_NUMBER(pin_number));
>    }
>
> -  RELEASE_LOCK(gpio_bank_state[bank].lock);
> +  RELEASE_LOCK(gpio_bank_state[locked_bank].lock);
>
>    return RTEMS_SUCCESSFUL;
>  }
> --
> 1.9.1
>
>
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