[PATCH] phy: exynos-mipi-video: avoid uninitialized variable use

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[PATCH] phy: exynos-mipi-video: avoid uninitialized variable use

Arnd Bergmann
A rework of the exynos-mipi-video driver caused a warning
about the new __set_phy_state function potentially accessing
a variable before its initialization:

drivers/phy/phy-exynos-mipi-video.c: In function '__set_phy_state':
drivers/phy/phy-exynos-mipi-video.c:238:13: error: 'val' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  return val & data->resetn_val;
         ~~~~^~~~~~~~~~~~~~~~~~
drivers/phy/phy-exynos-mipi-video.c:235:6: note: 'val' was declared here
  u32 val;

The failure scenario here is the offset passed into a the
stub regmap_read() function that does not modify its output,
however regmap_read() can also fail for other reasons, so
adding error handling (in this case, returning zero from
is_running) seems the best solution.

Note that this warning showed up with the ARM s5pv210_defconfig,
indicating that we most likely want to either enable CONFIG_REGMAP
in that defconfig as well, or disable the phy-exynos-mipi-video
driver.

Signed-off-by: Arnd Bergmann <[hidden email]>
Fixes: 97a3042f7616 ("phy: exynos-mipi-video: Rewrite handling of phy registers")
---
 drivers/phy/phy-exynos-mipi-video.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/phy/phy-exynos-mipi-video.c b/drivers/phy/phy-exynos-mipi-video.c
index cc093ebfda94..8b851f718123 100644
--- a/drivers/phy/phy-exynos-mipi-video.c
+++ b/drivers/phy/phy-exynos-mipi-video.c
@@ -233,8 +233,12 @@ static inline int __is_running(const struct exynos_mipi_phy_desc *data,
  struct exynos_mipi_video_phy *state)
 {
  u32 val;
+ int ret;
+
+ ret = regmap_read(state->regmaps[data->resetn_map], data->resetn_reg, &val);
+ if (ret)
+ return 0;
 
- regmap_read(state->regmaps[data->resetn_map], data->resetn_reg, &val);
  return val & data->resetn_val;
 }
 
--
2.7.0

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Re: [PATCH] phy: exynos-mipi-video: avoid uninitialized variable use

Krzysztof Kozlowski-3
On Wed, May 11, 2016 at 02:49:53PM +0200, Arnd Bergmann wrote:

> A rework of the exynos-mipi-video driver caused a warning
> about the new __set_phy_state function potentially accessing
> a variable before its initialization:
>
> drivers/phy/phy-exynos-mipi-video.c: In function '__set_phy_state':
> drivers/phy/phy-exynos-mipi-video.c:238:13: error: 'val' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>   return val & data->resetn_val;
>          ~~~~^~~~~~~~~~~~~~~~~~
> drivers/phy/phy-exynos-mipi-video.c:235:6: note: 'val' was declared here
>   u32 val;
>
> The failure scenario here is the offset passed into a the
> stub regmap_read() function that does not modify its output,
> however regmap_read() can also fail for other reasons, so
> adding error handling (in this case, returning zero from
> is_running) seems the best solution.
>
> Note that this warning showed up with the ARM s5pv210_defconfig,
> indicating that we most likely want to either enable CONFIG_REGMAP
> in that defconfig as well, or disable the phy-exynos-mipi-video
> driver.
>
> Signed-off-by: Arnd Bergmann <[hidden email]>
> Fixes: 97a3042f7616 ("phy: exynos-mipi-video: Rewrite handling of phy registers")
> ---
>  drivers/phy/phy-exynos-mipi-video.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/phy/phy-exynos-mipi-video.c b/drivers/phy/phy-exynos-mipi-video.c
> index cc093ebfda94..8b851f718123 100644
> --- a/drivers/phy/phy-exynos-mipi-video.c
> +++ b/drivers/phy/phy-exynos-mipi-video.c
> @@ -233,8 +233,12 @@ static inline int __is_running(const struct exynos_mipi_phy_desc *data,
>   struct exynos_mipi_video_phy *state)
>  {
>   u32 val;

Other way would be to initialize val=0 since there is no real error code
returned. Anyway:

Reviewed-by: Krzysztof Kozlowski <[hidden email]>

Best regards,
Krzysztof

> + int ret;
> +
> + ret = regmap_read(state->regmaps[data->resetn_map], data->resetn_reg, &val);
> + if (ret)
> + return 0;
>  
> - regmap_read(state->regmaps[data->resetn_map], data->resetn_reg, &val);
>   return val & data->resetn_val;
>  }
>  
> --
> 2.7.0
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in
> the body of a message to [hidden email]
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
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Re: [PATCH] phy: exynos-mipi-video: avoid uninitialized variable use

Arnd Bergmann
On Wednesday, May 11, 2016 8:51:55 PM CEST Krzysztof Kozlowski wrote:

> On Wed, May 11, 2016 at 02:49:53PM +0200, Arnd Bergmann wrote:
> > A rework of the exynos-mipi-video driver caused a warning
> > about the new __set_phy_state function potentially accessing
> > a variable before its initialization:
> >
> > drivers/phy/phy-exynos-mipi-video.c: In function '__set_phy_state':
> > drivers/phy/phy-exynos-mipi-video.c:238:13: error: 'val' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> >   return val & data->resetn_val;
> >          ~~~~^~~~~~~~~~~~~~~~~~
> > drivers/phy/phy-exynos-mipi-video.c:235:6: note: 'val' was declared here
> >   u32 val;
> >
> > The failure scenario here is the offset passed into a the
> > stub regmap_read() function that does not modify its output,
> > however regmap_read() can also fail for other reasons, so
> > adding error handling (in this case, returning zero from
> > is_running) seems the best solution.
> >
> > Note that this warning showed up with the ARM s5pv210_defconfig,
> > indicating that we most likely want to either enable CONFIG_REGMAP
> > in that defconfig as well, or disable the phy-exynos-mipi-video
> > driver.
> >
> > Signed-off-by: Arnd Bergmann <[hidden email]>
> > Fixes: 97a3042f7616 ("phy: exynos-mipi-video: Rewrite handling of phy registers")
> > ---
> >  drivers/phy/phy-exynos-mipi-video.c | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/phy/phy-exynos-mipi-video.c b/drivers/phy/phy-exynos-mipi-video.c
> > index cc093ebfda94..8b851f718123 100644
> > --- a/drivers/phy/phy-exynos-mipi-video.c
> > +++ b/drivers/phy/phy-exynos-mipi-video.c
> > @@ -233,8 +233,12 @@ static inline int __is_running(const struct exynos_mipi_phy_desc *data,
> >                       struct exynos_mipi_video_phy *state)
> >  {
> >       u32 val;
>
> Other way would be to initialize val=0 since there is no real error code
> returned. Anyway:
>
> Reviewed-by: Krzysztof Kozlowski <[hidden email]>


This hasn't made it into linux-next yet, any chance we'll see it in -rc1 or -rc2?

        Arnd
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Re: [PATCH] phy: exynos-mipi-video: avoid uninitialized variable use

Kishon Vijay Abraham I
Hi Arnd,

On Thursday 26 May 2016 12:24 AM, Arnd Bergmann wrote:

> On Wednesday, May 11, 2016 8:51:55 PM CEST Krzysztof Kozlowski wrote:
>> On Wed, May 11, 2016 at 02:49:53PM +0200, Arnd Bergmann wrote:
>>> A rework of the exynos-mipi-video driver caused a warning
>>> about the new __set_phy_state function potentially accessing
>>> a variable before its initialization:
>>>
>>> drivers/phy/phy-exynos-mipi-video.c: In function '__set_phy_state':
>>> drivers/phy/phy-exynos-mipi-video.c:238:13: error: 'val' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>>>   return val & data->resetn_val;
>>>          ~~~~^~~~~~~~~~~~~~~~~~
>>> drivers/phy/phy-exynos-mipi-video.c:235:6: note: 'val' was declared here
>>>   u32 val;
>>>
>>> The failure scenario here is the offset passed into a the
>>> stub regmap_read() function that does not modify its output,
>>> however regmap_read() can also fail for other reasons, so
>>> adding error handling (in this case, returning zero from
>>> is_running) seems the best solution.
>>>
>>> Note that this warning showed up with the ARM s5pv210_defconfig,
>>> indicating that we most likely want to either enable CONFIG_REGMAP
>>> in that defconfig as well, or disable the phy-exynos-mipi-video
>>> driver.
>>>
>>> Signed-off-by: Arnd Bergmann <[hidden email]>
>>> Fixes: 97a3042f7616 ("phy: exynos-mipi-video: Rewrite handling of phy registers")
>>> ---
>>>  drivers/phy/phy-exynos-mipi-video.c | 6 +++++-
>>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/phy/phy-exynos-mipi-video.c b/drivers/phy/phy-exynos-mipi-video.c
>>> index cc093ebfda94..8b851f718123 100644
>>> --- a/drivers/phy/phy-exynos-mipi-video.c
>>> +++ b/drivers/phy/phy-exynos-mipi-video.c
>>> @@ -233,8 +233,12 @@ static inline int __is_running(const struct exynos_mipi_phy_desc *data,
>>>                       struct exynos_mipi_video_phy *state)
>>>  {
>>>       u32 val;
>>
>> Other way would be to initialize val=0 since there is no real error code
>> returned. Anyway:
>>
>> Reviewed-by: Krzysztof Kozlowski <[hidden email]>
>
>
> This hasn't made it into linux-next yet, any chance we'll see it in -rc1 or -rc2?

Not in -rc1. Mostly it'll go in -rc2. Generally I start queuing patches after
-rc1 is tagged.

Thanks
Kishon