[patch] drm/amd: cleanup get_mfd_cell_dev()

[patch] drm/amd: cleanup get_mfd_cell_dev()

[Dan Carpenter]

It's simpler to just use snprintf() to print this to one buffer instead
of using strcpy() and strcat().  Also using snprintf() is slightly safer
than using sprintf().

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
index 9f8cfaa..d6b0bff 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
@@ -240,12 +240,10 @@ static int acp_poweron(struct generic_pm_domain *genpd)
 static struct device *get_mfd_cell_dev(const char *device_name, int r)
 {
 	char auto_dev_name[25];
-	char buf[8];
 	struct device *dev;
 
-	sprintf(buf, ".%d.auto", r);
-	strcpy(auto_dev_name, device_name);
-	strcat(auto_dev_name, buf);
+	snprintf(auto_dev_name, sizeof(auto_dev_name),
+		 "%s.%d.auto", device_name, r);
 	dev = bus_find_device_by_name(&platform_bus_type, NULL, auto_dev_name);
 	dev_info(dev, "device %s added to pm domain\n", auto_dev_name);
 
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Re: [patch] drm/amd: cleanup get_mfd_cell_dev()

[Alex Deucher]

On Thu, Feb 25, 2016 at 2:47 AM, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> It's simpler to just use snprintf() to print this to one buffer instead
> of using strcpy() and strcat().  Also using snprintf() is slightly safer
> than using sprintf().
>
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Applied.  Thanks!

>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
> index 9f8cfaa..d6b0bff 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
> @@ -240,12 +240,10 @@ static int acp_poweron(struct generic_pm_domain *genpd)
>  static struct device *get_mfd_cell_dev(const char *device_name, int r)
>  {
>         char auto_dev_name[25];
> -       char buf[8];
>         struct device *dev;
>
> -       sprintf(buf, ".%d.auto", r);
> -       strcpy(auto_dev_name, device_name);
> -       strcat(auto_dev_name, buf);
> +       snprintf(auto_dev_name, sizeof(auto_dev_name),
> +                "%s.%d.auto", device_name, r);
>         dev = bus_find_device_by_name(&platform_bus_type, NULL, auto_dev_name);
>         dev_info(dev, "device %s added to pm domain\n", auto_dev_name);
>
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Re: [patch] drm/amd: cleanup get_mfd_cell_dev()

[walter harms]

Am 25.02.2016 08:47, schrieb Dan Carpenter:
> It's simpler to just use snprintf() to print this to one buffer instead
> of using strcpy() and strcat().  Also using snprintf() is slightly safer
> than using sprintf().
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
> index 9f8cfaa..d6b0bff 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
> @@ -240,12 +240,10 @@ static int acp_poweron(struct generic_pm_domain *genpd)
>  static struct device *get_mfd_cell_dev(const char *device_name, int r)
>  {
>  	char auto_dev_name[25];
> -	char buf[8];
>  	struct device *dev;
>  
> -	sprintf(buf, ".%d.auto", r);
> -	strcpy(auto_dev_name, device_name);
> -	strcat(auto_dev_name, buf);
> +	snprintf(auto_dev_name, sizeof(auto_dev_name),
> +		 "%s.%d.auto", device_name, r);
>  	dev = bus_find_device_by_name(&platform_bus_type, NULL, auto_dev_name);
>  	dev_info(dev, "device %s added to pm domain\n", auto_dev_name);
>  

hi,
i tried to understand what is the base for char auto_dev_name[25]. It is not clear
from these snipped if that is large or small.

(To be aware i assume that
get_mfd_cell_dev("terrible_long_and_Stupid_name",1234567899346712) will never happen
but i could find no reason)

A small comment that explains the magic 25 would be nice.

re,
 wh

Re: [patch] drm/amd: cleanup get_mfd_cell_dev()

[Dan Carpenter]

On Sat, Feb 27, 2016 at 10:50:40AM +0100, walter harms wrote:
> 
> 
> Am 25.02.2016 08:47, schrieb Dan Carpenter:
> > It's simpler to just use snprintf() to print this to one buffer instead
> > of using strcpy() and strcat().  Also using snprintf() is slightly safer
> > than using sprintf().
> > 
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > 
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
> > index 9f8cfaa..d6b0bff 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
> > @@ -240,12 +240,10 @@ static int acp_poweron(struct generic_pm_domain *genpd)
> >  static struct device *get_mfd_cell_dev(const char *device_name, int r)
> >  {
> >  	char auto_dev_name[25];
> > -	char buf[8];
> >  	struct device *dev;
> >  
> > -	sprintf(buf, ".%d.auto", r);
> > -	strcpy(auto_dev_name, device_name);
> > -	strcat(auto_dev_name, buf);
> > +	snprintf(auto_dev_name, sizeof(auto_dev_name),
> > +		 "%s.%d.auto", device_name, r);
> >  	dev = bus_find_device_by_name(&platform_bus_type, NULL, auto_dev_name);
> >  	dev_info(dev, "device %s added to pm domain\n", auto_dev_name);
> >  
> 
> hi,
> i tried to understand what is the base for char auto_dev_name[25]. It is not clear
> from these snipped if that is large or small.
> 
> (To be aware i assume that
> get_mfd_cell_dev("terrible_long_and_Stupid_name",1234567899346712) will never happen
> but i could find no reason)
> 
> A small comment that explains the magic 25 would be nice.

I have no idea, either of course.  For example,
mc13xxx_add_subdevice_pdata() assumes device_name by itself can be 30
characters.  Hence the change to snprintf.

regards,
dan carpenter

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Re: [patch] drm/amd: cleanup get_mfd_cell_dev()

[walter harms]

Am 27.02.2016 11:40, schrieb Dan Carpenter:
> On Sat, Feb 27, 2016 at 10:50:40AM +0100, walter harms wrote:
>>
>>
>> Am 25.02.2016 08:47, schrieb Dan Carpenter:
>>> It's simpler to just use snprintf() to print this to one buffer instead
>>> of using strcpy() and strcat().  Also using snprintf() is slightly safer
>>> than using sprintf().
>>>
>>> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
>>> index 9f8cfaa..d6b0bff 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
>>> @@ -240,12 +240,10 @@ static int acp_poweron(struct generic_pm_domain *genpd)
>>>  static struct device *get_mfd_cell_dev(const char *device_name, int r)
>>>  {
>>>  	char auto_dev_name[25];
>>> -	char buf[8];
>>>  	struct device *dev;
>>>  
>>> -	sprintf(buf, ".%d.auto", r);
>>> -	strcpy(auto_dev_name, device_name);
>>> -	strcat(auto_dev_name, buf);
>>> +	snprintf(auto_dev_name, sizeof(auto_dev_name),
>>> +		 "%s.%d.auto", device_name, r);
>>>  	dev = bus_find_device_by_name(&platform_bus_type, NULL, auto_dev_name);
>>>  	dev_info(dev, "device %s added to pm domain\n", auto_dev_name);
>>>  
>>
>> hi,
>> i tried to understand what is the base for char auto_dev_name[25]. It is not clear
>> from these snipped if that is large or small.
>>
>> (To be aware i assume that
>> get_mfd_cell_dev("terrible_long_and_Stupid_name",1234567899346712) will never happen
>> but i could find no reason)
>>
>> A small comment that explains the magic 25 would be nice.
> 
> I have no idea, either of course.  For example,
> mc13xxx_add_subdevice_pdata() assumes device_name by itself can be 30
> characters.  Hence the change to snprintf.
> 

Hi Dan,
i also think that this limit is artificial, one of those "it works" things.
The problem is that i have seen changes in the naming als ready done, like the
shift from /dev/sda to things like /dev/disk/by-id/scsi-SATA_WDC_WD5000AAKS-_WD-WCASY5869245-part1
and you are out of the game here. snprintf will cut the tail and the %d.auto stuff is dead in the water.
To make it clear, I do not thing that is security related issue but it could result in annoying
failures. (the solution is obviously to use asprintf() and free the mem later :) ).

re,
 wh
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