* [PATCH v2][next] counter: Add default statement to switch() in quad8_function_read()
@ 2021-09-20 17:37 Tim Gardner
2021-09-21 0:36 ` William Breathitt Gray
0 siblings, 1 reply; 4+ messages in thread
From: Tim Gardner @ 2021-09-20 17:37 UTC (permalink / raw)
To: linux-iio
Cc: tim.gardner, William Breathitt Gray, Syed Nayyar Waris, linux-kernel
v2: Add the correct Cc's
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 returning an error.
Cc: William Breathitt Gray <vilhelm.gray@gmail.com>
Cc: Syed Nayyar Waris <syednwaris@gmail.com>
Cc: linux-iio@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
---
drivers/counter/104-quad-8.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
index c587f295d720..3a69d35b82ea 100644
--- a/drivers/counter/104-quad-8.c
+++ b/drivers/counter/104-quad-8.c
@@ -215,6 +215,8 @@ static int quad8_function_read(struct counter_device *counter,
case 2:
*function = COUNTER_FUNCTION_QUADRATURE_X4;
break;
+ default:
+ return -1;
}
else
*function = COUNTER_FUNCTION_PULSE_DIRECTION;
--
2.33.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v2][next] counter: Add default statement to switch() in quad8_function_read()
2021-09-20 17:37 [PATCH v2][next] counter: Add default statement to switch() in quad8_function_read() Tim Gardner
@ 2021-09-21 0:36 ` William Breathitt Gray
2021-09-21 13:37 ` [PATCH v3][next] " Tim Gardner
0 siblings, 1 reply; 4+ messages in thread
From: William Breathitt Gray @ 2021-09-21 0:36 UTC (permalink / raw)
To: Tim Gardner; +Cc: jic23, linux-iio, Syed Nayyar Waris, linux-kernel
[-- Attachment #1: Type: text/plain, Size: 2032 bytes --]
On Mon, Sep 20, 2021 at 11:37:37AM -0600, Tim Gardner wrote:
> v2: Add the correct Cc's
>
> 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 returning an error.
>
> Cc: William Breathitt Gray <vilhelm.gray@gmail.com>
> Cc: Syed Nayyar Waris <syednwaris@gmail.com>
> Cc: linux-iio@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Hello Tim,
The possible values of quadrature_scale are hardcoded in
quad8_function_write() so we should never have scale value greater than
2. But it would be a good idea to provide a default statement here to
pacify the warning, or at least mitigate shooting ourselves in the foot
in the future if this part of the code is changed.
Please add a comment similar to the default statement in
quad8_function_write() indicating that we should never reach this path,
and also return a more informative error code such as -EINVAL.
William Breathitt Gray
> ---
> drivers/counter/104-quad-8.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
> index c587f295d720..3a69d35b82ea 100644
> --- a/drivers/counter/104-quad-8.c
> +++ b/drivers/counter/104-quad-8.c
> @@ -215,6 +215,8 @@ static int quad8_function_read(struct counter_device *counter,
> case 2:
> *function = COUNTER_FUNCTION_QUADRATURE_X4;
> break;
> + default:
> + return -1;
> }
> else
> *function = COUNTER_FUNCTION_PULSE_DIRECTION;
> --
> 2.33.0
>
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH v3][next] counter: Add default statement to switch() in quad8_function_read()
2021-09-21 0:36 ` William Breathitt Gray
@ 2021-09-21 13:37 ` Tim Gardner
2021-09-21 22:51 ` William Breathitt Gray
0 siblings, 1 reply; 4+ messages in thread
From: Tim Gardner @ 2021-09-21 13:37 UTC (permalink / raw)
To: linux-iio
Cc: tim.gardner, William Breathitt Gray, Syed Nayyar Waris, linux-kernel
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@gmail.com>
Cc: Syed Nayyar Waris <syednwaris@gmail.com>
Cc: linux-iio@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
---
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
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v3][next] counter: Add default statement to switch() in quad8_function_read()
2021-09-21 13:37 ` [PATCH v3][next] " Tim Gardner
@ 2021-09-21 22:51 ` William Breathitt Gray
0 siblings, 0 replies; 4+ messages in thread
From: William Breathitt Gray @ 2021-09-21 22:51 UTC (permalink / raw)
To: Tim Gardner; +Cc: linux-iio, Syed Nayyar Waris, linux-kernel
[-- Attachment #1: Type: text/plain, Size: 2488 bytes --]
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@gmail.com>
> Cc: Syed Nayyar Waris <syednwaris@gmail.com>
> Cc: linux-iio@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
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@gmail.com>
> ---
> 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
>
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-09-21 22:51 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-09-20 17:37 [PATCH v2][next] counter: Add default statement to switch() in quad8_function_read() Tim Gardner
2021-09-21 0:36 ` William Breathitt Gray
2021-09-21 13:37 ` [PATCH v3][next] " Tim Gardner
2021-09-21 22:51 ` William Breathitt Gray
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.