On Tue, Sep 21, 2021 at 07:37:49AM -0600, Tim Gardner wrote:
> Coverity complains of a possible use of an uninitialized variable in
> quad8_action_read().
>
> CID 119643 (#1 of 1): Uninitialized scalar variable (UNINIT)
> 4. uninit_use: Using uninitialized value function.
> 346 switch (function) {
>
> The call to quad8_function_read() could theoretically return without assigning
> a value to '*function', thus causing the use of an ininitialized variable
> 'function' in quad8_action_read().
>
> Fix this by adding a default statement to the switch in quad8_function_read()
> and setting a return error code.
>
> Cc: William Breathitt Gray <vilhelm.gray@xxxxxxxxx>
> Cc: Syed Nayyar Waris <syednwaris@xxxxxxxxx>
> Cc: linux-iio@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Signed-off-by: Tim Gardner <tim.gardner@xxxxxxxxxxxxx>
Thank you for noticing the mutex. Although this case is simple, I'd
still prefer for this function to return early when an error is found
rather than hold a return value until the end. Please adjust the default
case to unlock the mutex directly and return immediately with -EINVAL.
With that change feel free to add my Ack-by line:
Acked-by: William Breathitt Gray <vilhelm.gray@xxxxxxxxx>
> ---
> v2 - Add the correct Cc's
> v3 - Add comment to the default switch statement. Also noticed v2 would have
> returned with a lock held. Fix that by returning a variable return code.
> ---
> drivers/counter/104-quad-8.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
> index c587f295d720..7faca6b760e7 100644
> --- a/drivers/counter/104-quad-8.c
> +++ b/drivers/counter/104-quad-8.c
> @@ -201,6 +201,7 @@ static int quad8_function_read(struct counter_device *counter,
> {
> struct quad8 *const priv = counter->priv;
> const int id = count->id;
> + int ret = 0;
>
> mutex_lock(&priv->lock);
>
> @@ -215,13 +216,16 @@ static int quad8_function_read(struct counter_device *counter,
> case 2:
> *function = COUNTER_FUNCTION_QUADRATURE_X4;
> break;
> + default:
> + /* should never reach this path */
> + ret = -EINVAL;
> }
> else
> *function = COUNTER_FUNCTION_PULSE_DIRECTION;
>
> mutex_unlock(&priv->lock);
>
> - return 0;
> + return ret;
> }
>
> static int quad8_function_write(struct counter_device *counter,
> --
> 2.33.0
>
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