[PATCH] iio: trigger: stm32-timer: fix the usage of uninitialized variables
From: Yizhuo
Date: Mon Sep 30 2019 - 16:44:15 EST
Several functions in this file are trying to use regmap_read() to
initialize the specific variable, however, if regmap_read() fails,
the variable could be uninitialized but used directly, which is
potentially unsafe. The return value of regmap_read() should be
checked and handled. This patch fixes most of the uninitialized
variables, but those in function stm32_tt_read_frequency() are
hard to handle and need extra effot.
Signed-off-by: Yizhuo <yzhai003@xxxxxxx>
---
drivers/iio/trigger/stm32-timer-trigger.c | 98 ++++++++++++++++++++---
1 file changed, 85 insertions(+), 13 deletions(-)
diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
index a5dfe65cd9b9..f8ea7bcbb739 100644
--- a/drivers/iio/trigger/stm32-timer-trigger.c
+++ b/drivers/iio/trigger/stm32-timer-trigger.c
@@ -107,6 +107,7 @@ static int stm32_timer_start(struct stm32_timer_trigger *priv,
unsigned long long prd, div;
int prescaler = 0;
u32 ccer, cr1;
+ int ret;
/* Period and prescaler values depends of clock rate */
div = (unsigned long long)clk_get_rate(priv->clk);
@@ -132,11 +133,21 @@ static int stm32_timer_start(struct stm32_timer_trigger *priv,
}
/* Check if nobody else use the timer */
- regmap_read(priv->regmap, TIM_CCER, &ccer);
+ ret = regmap_read(priv->regmap, TIM_CCER, &ccer);
+ if (ret) {
+ dev_err(priv->dev, "fail to read TIM_CCER.\n");
+ return ret;
+ }
+
if (ccer & TIM_CCER_CCXE)
return -EBUSY;
- regmap_read(priv->regmap, TIM_CR1, &cr1);
+ ret = regmap_read(priv->regmap, TIM_CR1, &cr1);
+ if (ret) {
+ dev_err(priv->dev, "fail to read TIM_CR1.\n");
+ return ret;
+ }
+
if (!(cr1 & TIM_CR1_CEN))
clk_enable(priv->clk);
@@ -164,12 +175,23 @@ static int stm32_timer_start(struct stm32_timer_trigger *priv,
static void stm32_timer_stop(struct stm32_timer_trigger *priv)
{
u32 ccer, cr1;
+ int ret;
+
+ ret = regmap_read(priv->regmap, TIM_CCER, &ccer);
+ if (ret) {
+ dev_err(priv->dev, "Fail to read TIM_CCER.\n");
+ return;
+ }
- regmap_read(priv->regmap, TIM_CCER, &ccer);
if (ccer & TIM_CCER_CCXE)
return;
- regmap_read(priv->regmap, TIM_CR1, &cr1);
+ ret = regmap_read(priv->regmap, TIM_CR1, &cr1);
+ if (ret) {
+ dev_err(priv->dev, "Fail to read TIM_CR1.\n");
+ return;
+ }
+
if (cr1 & TIM_CR1_CEN)
clk_disable(priv->clk);
@@ -403,20 +425,36 @@ static int stm32_counter_read_raw(struct iio_dev *indio_dev,
{
struct stm32_timer_trigger *priv = iio_priv(indio_dev);
u32 dat;
+ int ret;
switch (mask) {
case IIO_CHAN_INFO_RAW:
- regmap_read(priv->regmap, TIM_CNT, &dat);
+ ret = regmap_read(priv->regmap, TIM_CNT, &dat);
+ if (ret) {
+ dev_err(priv->dev, "fail to read TIM_CNT.\n");
+ return ret;
+ }
+
*val = dat;
return IIO_VAL_INT;
case IIO_CHAN_INFO_ENABLE:
- regmap_read(priv->regmap, TIM_CR1, &dat);
+ ret = regmap_read(priv->regmap, TIM_CR1, &dat);
+ if (ret) {
+ dev_err(priv->dev, "fail to read TIM_CR1.\n");
+ return ret;
+ }
+
*val = (dat & TIM_CR1_CEN) ? 1 : 0;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
- regmap_read(priv->regmap, TIM_SMCR, &dat);
+ ret = regmap_read(priv->regmap, TIM_SMCR, &dat);
+ if (ret) {
+ dev_err(priv->dev, "fail to read TIM_SMCR.\n");
+ return ret;
+ }
+
dat &= TIM_SMCR_SMS;
*val = 1;
@@ -438,6 +476,7 @@ static int stm32_counter_write_raw(struct iio_dev *indio_dev,
{
struct stm32_timer_trigger *priv = iio_priv(indio_dev);
u32 dat;
+ int ret;
switch (mask) {
case IIO_CHAN_INFO_RAW:
@@ -449,13 +488,23 @@ static int stm32_counter_write_raw(struct iio_dev *indio_dev,
case IIO_CHAN_INFO_ENABLE:
if (val) {
- regmap_read(priv->regmap, TIM_CR1, &dat);
+ ret = regmap_read(priv->regmap, TIM_CR1, &dat);
+ if (ret) {
+ dev_err(priv->dev, "fail to read TIM_CR1.\n");
+ return ret;
+ }
+
if (!(dat & TIM_CR1_CEN))
clk_enable(priv->clk);
regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN,
TIM_CR1_CEN);
} else {
- regmap_read(priv->regmap, TIM_CR1, &dat);
+ ret = regmap_read(priv->regmap, TIM_CR1, &dat);
+ if (ret) {
+ dev_err(priv->dev, "fail to read TIM_CR1.\n");
+ return ret;
+ }
+
regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN,
0);
if (dat & TIM_CR1_CEN)
@@ -517,8 +566,13 @@ static int stm32_get_trigger_mode(struct iio_dev *indio_dev,
{
struct stm32_timer_trigger *priv = iio_priv(indio_dev);
u32 smcr;
+ int ret;
- regmap_read(priv->regmap, TIM_SMCR, &smcr);
+ ret = regmap_read(priv->regmap, TIM_SMCR, &smcr);
+ if (ret) {
+ dev_err(priv->dev, "fail to read TIM_SMCR.\n");
+ return ret;
+ }
return (smcr & TIM_SMCR_SMS) == TIM_SMCR_SMS ? 0 : -EINVAL;
}
@@ -557,6 +611,7 @@ static int stm32_set_enable_mode(struct iio_dev *indio_dev,
struct stm32_timer_trigger *priv = iio_priv(indio_dev);
int sms = stm32_enable_mode2sms(mode);
u32 val;
+ int ret;
if (sms < 0)
return sms;
@@ -565,7 +620,12 @@ static int stm32_set_enable_mode(struct iio_dev *indio_dev,
* enable counter clock, so it can use it. Keeps it in sync with CEN.
*/
if (sms == 6) {
- regmap_read(priv->regmap, TIM_CR1, &val);
+ ret = regmap_read(priv->regmap, TIM_CR1, &val);
+ if (ret) {
+ dev_err(priv->dev, "fail to read TIM_CR1.\n");
+ return ret;
+ }
+
if (!(val & TIM_CR1_CEN))
clk_enable(priv->clk);
}
@@ -594,8 +654,14 @@ static int stm32_get_enable_mode(struct iio_dev *indio_dev,
{
struct stm32_timer_trigger *priv = iio_priv(indio_dev);
u32 smcr;
+ int ret;
+
+ ret = regmap_read(priv->regmap, TIM_SMCR, &smcr);
+ if (ret) {
+ dev_err(priv->dev, "fail to read TIM_SMCR.\n");
+ return ret;
+ }
- regmap_read(priv->regmap, TIM_SMCR, &smcr);
smcr &= TIM_SMCR_SMS;
return stm32_sms2enable_mode(smcr);
@@ -706,13 +772,19 @@ EXPORT_SYMBOL(is_stm32_timer_trigger);
static void stm32_timer_detect_trgo2(struct stm32_timer_trigger *priv)
{
u32 val;
+ int ret;
/*
* Master mode selection 2 bits can only be written and read back when
* timer supports it.
*/
regmap_update_bits(priv->regmap, TIM_CR2, TIM_CR2_MMS2, TIM_CR2_MMS2);
- regmap_read(priv->regmap, TIM_CR2, &val);
+ ret = regmap_read(priv->regmap, TIM_CR2, &val);
+ if (ret) {
+ dev_err(priv->dev, "fail to read TIM_CR2.\n");
+ return;
+ }
+
regmap_update_bits(priv->regmap, TIM_CR2, TIM_CR2_MMS2, 0);
priv->has_trgo2 = !!val;
}
--
2.17.1