2015-11-23 13:47:20

by Arnd Bergmann

Subject: [PATCH] backlight: adp88x0: fix uninitialized variable use

gcc correctly warns about both the adp8860 and adp8870 backlight
drivers using an uninitialized variable in their error handling
path:

drivers/video/backlight/adp8870_bl.c: In function 'adp8870_bl_ambient_light_zone_store':
drivers/video/backlight/adp8870_bl.c:811:11: warning: 'reg_val' may be used uninitialized in this function

This changes the code to only write back the data if it was
correctly read to start with.

As a side-note, the drivers are mostly identical, so I think they
should really be merged into one file to avoid having to fix every
bug twice.

Signed-off-by: Arnd Bergmann <[email protected]>

diff --git a/drivers/video/backlight/adp8860_bl.c b/drivers/video/backlight/adp8860_bl.c
index 98ffe71e8af2..f0d4c0324580 100644
--- a/drivers/video/backlight/adp8860_bl.c
+++ b/drivers/video/backlight/adp8860_bl.c
@@ -621,10 +621,12 @@ static ssize_t adp8860_bl_ambient_light_zone_store(struct device *dev,

/* Set user supplied ambient light zone */
mutex_lock(&data->lock);
- adp8860_read(data->client, ADP8860_CFGR, &reg_val);
- reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
- reg_val |= (val - 1) << CFGR_BLV_SHIFT;
- adp8860_write(data->client, ADP8860_CFGR, reg_val);
+ ret = adp8860_read(data->client, ADP8860_CFGR, &reg_val);
+ if (!ret) {
+ reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
+ reg_val |= (val - 1) << CFGR_BLV_SHIFT;
+ adp8860_write(data->client, ADP8860_CFGR, reg_val);
+ }
mutex_unlock(&data->lock);
}

diff --git a/drivers/video/backlight/adp8870_bl.c b/drivers/video/backlight/adp8870_bl.c
index 9d738352d7d4..21acac90fd77 100644
--- a/drivers/video/backlight/adp8870_bl.c
+++ b/drivers/video/backlight/adp8870_bl.c
@@ -807,10 +807,12 @@ static ssize_t adp8870_bl_ambient_light_zone_store(struct device *dev,

/* Set user supplied ambient light zone */
mutex_lock(&data->lock);
- adp8870_read(data->client, ADP8870_CFGR, &reg_val);
- reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
- reg_val |= (val - 1) << CFGR_BLV_SHIFT;
- adp8870_write(data->client, ADP8870_CFGR, reg_val);
+ ret = adp8870_read(data->client, ADP8870_CFGR, &reg_val);
+ if (!ret) {
+ reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
+ reg_val |= (val - 1) << CFGR_BLV_SHIFT;
+ adp8870_write(data->client, ADP8870_CFGR, reg_val);
+ }
mutex_unlock(&data->lock);
}

2015-11-23 13:59:20

by Hennerich, Michael

Subject: Re: [PATCH] backlight: adp88x0: fix uninitialized variable use

On 11/23/2015 02:44 PM, Arnd Bergmann wrote:
> gcc correctly warns about both the adp8860 and adp8870 backlight
> drivers using an uninitialized variable in their error handling
> path:
>
> drivers/video/backlight/adp8870_bl.c: In function 'adp8870_bl_ambient_light_zone_store':
> drivers/video/backlight/adp8870_bl.c:811:11: warning: 'reg_val' may be used uninitialized in this function
>
> This changes the code to only write back the data if it was
> correctly read to start with.
>
> As a side-note, the drivers are mostly identical, so I think they
> should really be merged into one file to avoid having to fix every
> bug twice.
>
> Signed-off-by: Arnd Bergmann <[email protected]>

Acked-by: Michael Hennerich <[email protected]>

>
> diff --git a/drivers/video/backlight/adp8860_bl.c b/drivers/video/backlight/adp8860_bl.c
> index 98ffe71e8af2..f0d4c0324580 100644
> --- a/drivers/video/backlight/adp8860_bl.c
> +++ b/drivers/video/backlight/adp8860_bl.c
> @@ -621,10 +621,12 @@ static ssize_t adp8860_bl_ambient_light_zone_store(struct device *dev,
>
> /* Set user supplied ambient light zone */
> mutex_lock(&data->lock);
> - adp8860_read(data->client, ADP8860_CFGR, &reg_val);
> - reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
> - reg_val |= (val - 1) << CFGR_BLV_SHIFT;
> - adp8860_write(data->client, ADP8860_CFGR, reg_val);
> + ret = adp8860_read(data->client, ADP8860_CFGR, &reg_val);
> + if (!ret) {
> + reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
> + reg_val |= (val - 1) << CFGR_BLV_SHIFT;
> + adp8860_write(data->client, ADP8860_CFGR, reg_val);
> + }
> mutex_unlock(&data->lock);
> }
>
> diff --git a/drivers/video/backlight/adp8870_bl.c b/drivers/video/backlight/adp8870_bl.c
> index 9d738352d7d4..21acac90fd77 100644
> --- a/drivers/video/backlight/adp8870_bl.c
> +++ b/drivers/video/backlight/adp8870_bl.c
> @@ -807,10 +807,12 @@ static ssize_t adp8870_bl_ambient_light_zone_store(struct device *dev,
>
> /* Set user supplied ambient light zone */
> mutex_lock(&data->lock);
> - adp8870_read(data->client, ADP8870_CFGR, &reg_val);
> - reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
> - reg_val |= (val - 1) << CFGR_BLV_SHIFT;
> - adp8870_write(data->client, ADP8870_CFGR, reg_val);
> + ret = adp8870_read(data->client, ADP8870_CFGR, &reg_val);
> + if (!ret) {
> + reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
> + reg_val |= (val - 1) << CFGR_BLV_SHIFT;
> + adp8870_write(data->client, ADP8870_CFGR, reg_val);
> + }
> mutex_unlock(&data->lock);
> }
>
>


--
Greetings,
Michael

--
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Sitz der Gesellschaft: Muenchen; Registergericht: Muenchen HRB 40368;
Geschaeftsfuehrer:Dr.Carsten Suckrow, Thomas Wessel, William A. Martin,
Margaret Seif

2015-11-23 14:41:01

by Lee Jones

Subject: Re: [PATCH] backlight: adp88x0: fix uninitialized variable use

On Mon, 23 Nov 2015, Arnd Bergmann wrote:

> gcc correctly warns about both the adp8860 and adp8870 backlight
> drivers using an uninitialized variable in their error handling
> path:
>
> drivers/video/backlight/adp8870_bl.c: In function 'adp8870_bl_ambient_light_zone_store':
> drivers/video/backlight/adp8870_bl.c:811:11: warning: 'reg_val' may be used uninitialized in this function
>
> This changes the code to only write back the data if it was
> correctly read to start with.
>
> As a side-note, the drivers are mostly identical, so I think they
> should really be merged into one file to avoid having to fix every
> bug twice.
>
> Signed-off-by: Arnd Bergmann <[email protected]>

Applied, thanks.

> diff --git a/drivers/video/backlight/adp8860_bl.c b/drivers/video/backlight/adp8860_bl.c
> index 98ffe71e8af2..f0d4c0324580 100644
> --- a/drivers/video/backlight/adp8860_bl.c
> +++ b/drivers/video/backlight/adp8860_bl.c
> @@ -621,10 +621,12 @@ static ssize_t adp8860_bl_ambient_light_zone_store(struct device *dev,
>
> /* Set user supplied ambient light zone */
> mutex_lock(&data->lock);
> - adp8860_read(data->client, ADP8860_CFGR, &reg_val);
> - reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
> - reg_val |= (val - 1) << CFGR_BLV_SHIFT;
> - adp8860_write(data->client, ADP8860_CFGR, reg_val);
> + ret = adp8860_read(data->client, ADP8860_CFGR, &reg_val);
> + if (!ret) {
> + reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
> + reg_val |= (val - 1) << CFGR_BLV_SHIFT;
> + adp8860_write(data->client, ADP8860_CFGR, reg_val);
> + }
> mutex_unlock(&data->lock);
> }
>
> diff --git a/drivers/video/backlight/adp8870_bl.c b/drivers/video/backlight/adp8870_bl.c
> index 9d738352d7d4..21acac90fd77 100644
> --- a/drivers/video/backlight/adp8870_bl.c
> +++ b/drivers/video/backlight/adp8870_bl.c
> @@ -807,10 +807,12 @@ static ssize_t adp8870_bl_ambient_light_zone_store(struct device *dev,
>
> /* Set user supplied ambient light zone */
> mutex_lock(&data->lock);
> - adp8870_read(data->client, ADP8870_CFGR, &reg_val);
> - reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
> - reg_val |= (val - 1) << CFGR_BLV_SHIFT;
> - adp8870_write(data->client, ADP8870_CFGR, reg_val);
> + ret = adp8870_read(data->client, ADP8870_CFGR, &reg_val);
> + if (!ret) {
> + reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
> + reg_val |= (val - 1) << CFGR_BLV_SHIFT;
> + adp8870_write(data->client, ADP8870_CFGR, reg_val);
> + }
> mutex_unlock(&data->lock);
> }
>
>

--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

2015-11-23 16:22:57

by Lee Jones

Subject: Re: [PATCH] backlight: adp88x0: fix uninitialized variable use

On Mon, 23 Nov 2015, Arnd Bergmann wrote:

> gcc correctly warns about both the adp8860 and adp8870 backlight
> drivers using an uninitialized variable in their error handling
> path:
>
> drivers/video/backlight/adp8870_bl.c: In function 'adp8870_bl_ambient_light_zone_store':
> drivers/video/backlight/adp8870_bl.c:811:11: warning: 'reg_val' may be used uninitialized in this function
>
> This changes the code to only write back the data if it was
> correctly read to start with.
>
> As a side-note, the drivers are mostly identical, so I think they
> should really be merged into one file to avoid having to fix every
> bug twice.
>
> Signed-off-by: Arnd Bergmann <[email protected]>

Applied with the $SUBJECT line fixed.

> diff --git a/drivers/video/backlight/adp8860_bl.c b/drivers/video/backlight/adp8860_bl.c
> index 98ffe71e8af2..f0d4c0324580 100644
> --- a/drivers/video/backlight/adp8860_bl.c
> +++ b/drivers/video/backlight/adp8860_bl.c
> @@ -621,10 +621,12 @@ static ssize_t adp8860_bl_ambient_light_zone_store(struct device *dev,
>
> /* Set user supplied ambient light zone */
> mutex_lock(&data->lock);
> - adp8860_read(data->client, ADP8860_CFGR, &reg_val);
> - reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
> - reg_val |= (val - 1) << CFGR_BLV_SHIFT;
> - adp8860_write(data->client, ADP8860_CFGR, reg_val);
> + ret = adp8860_read(data->client, ADP8860_CFGR, &reg_val);
> + if (!ret) {
> + reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
> + reg_val |= (val - 1) << CFGR_BLV_SHIFT;
> + adp8860_write(data->client, ADP8860_CFGR, reg_val);
> + }
> mutex_unlock(&data->lock);
> }
>
> diff --git a/drivers/video/backlight/adp8870_bl.c b/drivers/video/backlight/adp8870_bl.c
> index 9d738352d7d4..21acac90fd77 100644
> --- a/drivers/video/backlight/adp8870_bl.c
> +++ b/drivers/video/backlight/adp8870_bl.c
> @@ -807,10 +807,12 @@ static ssize_t adp8870_bl_ambient_light_zone_store(struct device *dev,
>
> /* Set user supplied ambient light zone */
> mutex_lock(&data->lock);
> - adp8870_read(data->client, ADP8870_CFGR, &reg_val);
> - reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
> - reg_val |= (val - 1) << CFGR_BLV_SHIFT;
> - adp8870_write(data->client, ADP8870_CFGR, reg_val);
> + ret = adp8870_read(data->client, ADP8870_CFGR, &reg_val);
> + if (!ret) {
> + reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT);
> + reg_val |= (val - 1) << CFGR_BLV_SHIFT;
> + adp8870_write(data->client, ADP8870_CFGR, reg_val);
> + }
> mutex_unlock(&data->lock);
> }
>
>

--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog