* [PATCH] [v2] staging: iio: ad5933: avoid uninitialized variable in error case
@ 2016-10-24 15:22 Arnd Bergmann
2016-10-25 16:57 ` Jonathan Cameron
0 siblings, 1 reply; 4+ messages in thread
From: Arnd Bergmann @ 2016-10-24 15:22 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: Arnd Bergmann, Lars-Peter Clausen, Michael Hennerich,
Jonathan Cameron, Hartmut Knaack, Peter Meerwald-Stadler,
Alison Schofield, linux-iio, devel, linux-kernel
The ad5933_i2c_read function returns an error code to indicate
whether it could read data or not. However ad5933_work() ignores
this return code and just accesses the data unconditionally,
which gets detected by gcc as a possible bug:
drivers/staging/iio/impedance-analyzer/ad5933.c: In function 'ad5933_work':
drivers/staging/iio/impedance-analyzer/ad5933.c:649:16: warning: 'status' may be used uninitialized in this function [-Wmaybe-uninitialized]
This adds minimal error handling so we only evaluate the
data if it was correctly read.
Link: https://patchwork.kernel.org/patch/8110281/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2: handle failure for both affected reads instead of just the one
we get a warning for
v2: do not retry on failure to avoid looping in case of permanent
errors
---
drivers/staging/iio/impedance-analyzer/ad5933.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/drivers/staging/iio/impedance-analyzer/ad5933.c b/drivers/staging/iio/impedance-analyzer/ad5933.c
index 5eecf1cb1028..3892a7470410 100644
--- a/drivers/staging/iio/impedance-analyzer/ad5933.c
+++ b/drivers/staging/iio/impedance-analyzer/ad5933.c
@@ -655,6 +655,7 @@ static void ad5933_work(struct work_struct *work)
__be16 buf[2];
int val[2];
unsigned char status;
+ int ret;
mutex_lock(&indio_dev->mlock);
if (st->state == AD5933_CTRL_INIT_START_FREQ) {
@@ -662,19 +663,22 @@ static void ad5933_work(struct work_struct *work)
ad5933_cmd(st, AD5933_CTRL_START_SWEEP);
st->state = AD5933_CTRL_START_SWEEP;
schedule_delayed_work(&st->work, st->poll_time_jiffies);
- mutex_unlock(&indio_dev->mlock);
- return;
+ goto out;
}
- ad5933_i2c_read(st->client, AD5933_REG_STATUS, 1, &status);
+ ret = ad5933_i2c_read(st->client, AD5933_REG_STATUS, 1, &status);
+ if (ret)
+ goto out;
if (status & AD5933_STAT_DATA_VALID) {
int scan_count = bitmap_weight(indio_dev->active_scan_mask,
indio_dev->masklength);
- ad5933_i2c_read(st->client,
+ ret = ad5933_i2c_read(st->client,
test_bit(1, indio_dev->active_scan_mask) ?
AD5933_REG_REAL_DATA : AD5933_REG_IMAG_DATA,
scan_count * 2, (u8 *)buf);
+ if (ret)
+ goto out;
if (scan_count == 2) {
val[0] = be16_to_cpu(buf[0]);
@@ -686,8 +690,7 @@ static void ad5933_work(struct work_struct *work)
} else {
/* no data available - try again later */
schedule_delayed_work(&st->work, st->poll_time_jiffies);
- mutex_unlock(&indio_dev->mlock);
- return;
+ goto out;
}
if (status & AD5933_STAT_SWEEP_DONE) {
@@ -700,7 +703,7 @@ static void ad5933_work(struct work_struct *work)
ad5933_cmd(st, AD5933_CTRL_INC_FREQ);
schedule_delayed_work(&st->work, st->poll_time_jiffies);
}
-
+out:
mutex_unlock(&indio_dev->mlock);
}
--
2.9.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] [v2] staging: iio: ad5933: avoid uninitialized variable in error case
2016-10-24 15:22 [PATCH] [v2] staging: iio: ad5933: avoid uninitialized variable in error case Arnd Bergmann
@ 2016-10-25 16:57 ` Jonathan Cameron
2016-10-25 17:00 ` Lars-Peter Clausen
0 siblings, 1 reply; 4+ messages in thread
From: Jonathan Cameron @ 2016-10-25 16:57 UTC (permalink / raw)
To: Arnd Bergmann, Greg Kroah-Hartman
Cc: Lars-Peter Clausen, Michael Hennerich, Hartmut Knaack,
Peter Meerwald-Stadler, Alison Schofield, linux-iio, devel,
linux-kernel
On 24/10/16 16:22, Arnd Bergmann wrote:
> The ad5933_i2c_read function returns an error code to indicate
> whether it could read data or not. However ad5933_work() ignores
> this return code and just accesses the data unconditionally,
> which gets detected by gcc as a possible bug:
>
> drivers/staging/iio/impedance-analyzer/ad5933.c: In function 'ad5933_work':
> drivers/staging/iio/impedance-analyzer/ad5933.c:649:16: warning: 'status' may be used uninitialized in this function [-Wmaybe-uninitialized]
>
> This adds minimal error handling so we only evaluate the
> data if it was correctly read.
>
> Link: https://patchwork.kernel.org/patch/8110281/
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Looks good to me.
Lars?
> ---
> v2: handle failure for both affected reads instead of just the one
> we get a warning for
> v2: do not retry on failure to avoid looping in case of permanent
> errors
> ---
> drivers/staging/iio/impedance-analyzer/ad5933.c | 17 ++++++++++-------
> 1 file changed, 10 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/staging/iio/impedance-analyzer/ad5933.c b/drivers/staging/iio/impedance-analyzer/ad5933.c
> index 5eecf1cb1028..3892a7470410 100644
> --- a/drivers/staging/iio/impedance-analyzer/ad5933.c
> +++ b/drivers/staging/iio/impedance-analyzer/ad5933.c
> @@ -655,6 +655,7 @@ static void ad5933_work(struct work_struct *work)
> __be16 buf[2];
> int val[2];
> unsigned char status;
> + int ret;
>
> mutex_lock(&indio_dev->mlock);
> if (st->state == AD5933_CTRL_INIT_START_FREQ) {
> @@ -662,19 +663,22 @@ static void ad5933_work(struct work_struct *work)
> ad5933_cmd(st, AD5933_CTRL_START_SWEEP);
> st->state = AD5933_CTRL_START_SWEEP;
> schedule_delayed_work(&st->work, st->poll_time_jiffies);
> - mutex_unlock(&indio_dev->mlock);
> - return;
> + goto out;
> }
>
> - ad5933_i2c_read(st->client, AD5933_REG_STATUS, 1, &status);
> + ret = ad5933_i2c_read(st->client, AD5933_REG_STATUS, 1, &status);
> + if (ret)
> + goto out;
>
> if (status & AD5933_STAT_DATA_VALID) {
> int scan_count = bitmap_weight(indio_dev->active_scan_mask,
> indio_dev->masklength);
> - ad5933_i2c_read(st->client,
> + ret = ad5933_i2c_read(st->client,
> test_bit(1, indio_dev->active_scan_mask) ?
> AD5933_REG_REAL_DATA : AD5933_REG_IMAG_DATA,
> scan_count * 2, (u8 *)buf);
> + if (ret)
> + goto out;
>
> if (scan_count == 2) {
> val[0] = be16_to_cpu(buf[0]);
> @@ -686,8 +690,7 @@ static void ad5933_work(struct work_struct *work)
> } else {
> /* no data available - try again later */
> schedule_delayed_work(&st->work, st->poll_time_jiffies);
> - mutex_unlock(&indio_dev->mlock);
> - return;
> + goto out;
> }
>
> if (status & AD5933_STAT_SWEEP_DONE) {
> @@ -700,7 +703,7 @@ static void ad5933_work(struct work_struct *work)
> ad5933_cmd(st, AD5933_CTRL_INC_FREQ);
> schedule_delayed_work(&st->work, st->poll_time_jiffies);
> }
> -
> +out:
> mutex_unlock(&indio_dev->mlock);
> }
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] [v2] staging: iio: ad5933: avoid uninitialized variable in error case
2016-10-25 16:57 ` Jonathan Cameron
@ 2016-10-25 17:00 ` Lars-Peter Clausen
2016-10-25 17:31 ` Jonathan Cameron
0 siblings, 1 reply; 4+ messages in thread
From: Lars-Peter Clausen @ 2016-10-25 17:00 UTC (permalink / raw)
To: Jonathan Cameron, Arnd Bergmann, Greg Kroah-Hartman
Cc: Michael Hennerich, Hartmut Knaack, Peter Meerwald-Stadler,
Alison Schofield, linux-iio, devel, linux-kernel
On 10/25/2016 06:57 PM, Jonathan Cameron wrote:
> On 24/10/16 16:22, Arnd Bergmann wrote:
>> The ad5933_i2c_read function returns an error code to indicate
>> whether it could read data or not. However ad5933_work() ignores
>> this return code and just accesses the data unconditionally,
>> which gets detected by gcc as a possible bug:
>>
>> drivers/staging/iio/impedance-analyzer/ad5933.c: In function 'ad5933_work':
>> drivers/staging/iio/impedance-analyzer/ad5933.c:649:16: warning: 'status' may be used uninitialized in this function [-Wmaybe-uninitialized]
>>
>> This adds minimal error handling so we only evaluate the
>> data if it was correctly read.
>>
>> Link: https://patchwork.kernel.org/patch/8110281/
>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Looks good to me.
>
> Lars?
>
Looks good, thanks.
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] [v2] staging: iio: ad5933: avoid uninitialized variable in error case
2016-10-25 17:00 ` Lars-Peter Clausen
@ 2016-10-25 17:31 ` Jonathan Cameron
0 siblings, 0 replies; 4+ messages in thread
From: Jonathan Cameron @ 2016-10-25 17:31 UTC (permalink / raw)
To: Lars-Peter Clausen, Arnd Bergmann, Greg Kroah-Hartman
Cc: Michael Hennerich, Hartmut Knaack, Peter Meerwald-Stadler,
Alison Schofield, linux-iio, devel, linux-kernel
On 25/10/16 18:00, Lars-Peter Clausen wrote:
> On 10/25/2016 06:57 PM, Jonathan Cameron wrote:
>> On 24/10/16 16:22, Arnd Bergmann wrote:
>>> The ad5933_i2c_read function returns an error code to indicate
>>> whether it could read data or not. However ad5933_work() ignores
>>> this return code and just accesses the data unconditionally,
>>> which gets detected by gcc as a possible bug:
>>>
>>> drivers/staging/iio/impedance-analyzer/ad5933.c: In function 'ad5933_work':
>>> drivers/staging/iio/impedance-analyzer/ad5933.c:649:16: warning: 'status' may be used uninitialized in this function [-Wmaybe-uninitialized]
>>>
>>> This adds minimal error handling so we only evaluate the
>>> data if it was correctly read.
>>>
>>> Link: https://patchwork.kernel.org/patch/8110281/
>>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>> Looks good to me.
>>
>> Lars?
>>
>
> Looks good, thanks.
>
> Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Applied to the fixes-togreg branch of iio.git and marked for stable.
thanks,
Jonathan
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^ permalink raw reply [flat|nested] 4+ messages in thread
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2016-10-24 15:22 [PATCH] [v2] staging: iio: ad5933: avoid uninitialized variable in error case Arnd Bergmann
2016-10-25 16:57 ` Jonathan Cameron
2016-10-25 17:00 ` Lars-Peter Clausen
2016-10-25 17:31 ` Jonathan Cameron
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