[PATCH] pwm: sun4i: fix a possible NULL dereference

[PATCH] pwm: sun4i: fix a possible NULL dereference

[LABBE Corentin]

of_match_device could return NULL, and so cause a NULL pointer
dereference later.

Reported-by: coverity (CID 1324139)
Signed-off-by: LABBE Corentin <clabbe.montjoie@gmail.com>
---
 drivers/pwm/pwm-sun4i.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
index cd9dde5..3011fcc 100644
--- a/drivers/pwm/pwm-sun4i.c
+++ b/drivers/pwm/pwm-sun4i.c
@@ -291,6 +291,8 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
 	const struct of_device_id *match;
 
 	match = of_match_device(sun4i_pwm_dt_ids, &pdev->dev);
+	if (!match)
+		return -ENODEV;
 
 	pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
 	if (!pwm)
-- 
2.4.10

Re: [PATCH] pwm: sun4i: fix a possible NULL dereference

[Thierry Reding]

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On Thu, Nov 12, 2015 at 08:42:12AM +0100, LABBE Corentin wrote:
> of_match_device could return NULL, and so cause a NULL pointer
> dereference later.
> 
> Reported-by: coverity (CID 1324139)
> Signed-off-by: LABBE Corentin <clabbe.montjoie@gmail.com>
> ---
>  drivers/pwm/pwm-sun4i.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
> index cd9dde5..3011fcc 100644
> --- a/drivers/pwm/pwm-sun4i.c
> +++ b/drivers/pwm/pwm-sun4i.c
> @@ -291,6 +291,8 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
>  	const struct of_device_id *match;
>  
>  	match = of_match_device(sun4i_pwm_dt_ids, &pdev->dev);
> +	if (!match)
> +		return -ENODEV;

I explained this in a reply to another similar patch, but that was a
different audience, so here goes again: the driver core will use the
same device ID table to match on the driver, so the case where NULL
would be returned is the same case in which sun4i_pwm_probe() would
never have been called in the first place.

Thierry

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Re: [PATCH] pwm: sun4i: fix a possible NULL dereference

[Alexandre Belloni]

Hi,

On 12/11/2015 at 08:42:12 +0100, LABBE Corentin wrote :
> of_match_device could return NULL, and so cause a NULL pointer
> dereference later.
> 
> Reported-by: coverity (CID 1324139)
> Signed-off-by: LABBE Corentin <clabbe.montjoie@gmail.com>
> ---
>  drivers/pwm/pwm-sun4i.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
> index cd9dde5..3011fcc 100644
> --- a/drivers/pwm/pwm-sun4i.c
> +++ b/drivers/pwm/pwm-sun4i.c
> @@ -291,6 +291,8 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
>  	const struct of_device_id *match;
>  
>  	match = of_match_device(sun4i_pwm_dt_ids, &pdev->dev);
> +	if (!match)
> +		return -ENODEV;
>  

This will never happen. If it is not matching, then sun4i_pwm_probe is
not called.


-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com