[PATCH] [media] cx18: introduce a helper function to void array overrun

[PATCH] [media] cx18: introduce a helper function to void array overrun

[Ethan Zhao]

cx18_i2c_register() is called in cx18_init_subdevs() with index
greater than length of hw_bus array, that will cause array overrun,
introduce a helper cx18_get_max_bus_num() to void it.

Signed-off-by: Ethan Zhao <ethan.kernel@gmail.com>
---
 drivers/media/pci/cx18/cx18-driver.c | 2 +-
 drivers/media/pci/cx18/cx18-i2c.c    | 5 +++++
 drivers/media/pci/cx18/cx18-i2c.h    | 1 +
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/media/pci/cx18/cx18-driver.c b/drivers/media/pci/cx18/cx18-driver.c
index 6386ced..dadcd4a 100644
--- a/drivers/media/pci/cx18/cx18-driver.c
+++ b/drivers/media/pci/cx18/cx18-driver.c
@@ -856,7 +856,7 @@ static void cx18_init_subdevs(struct cx18 *cx)
 	u32 device;
 	int i;
 
-	for (i = 0, device = 1; i < 32; i++, device <<= 1) {
+	for (i = 0, device = 1; i < cx18_get_max_bus_num(); i++, device <<= 1) {
 
 		if (!(device & hw))
 			continue;
diff --git a/drivers/media/pci/cx18/cx18-i2c.c b/drivers/media/pci/cx18/cx18-i2c.c
index 4af8cd6..e0e8193 100644
--- a/drivers/media/pci/cx18/cx18-i2c.c
+++ b/drivers/media/pci/cx18/cx18-i2c.c
@@ -108,6 +108,11 @@ static int cx18_i2c_new_ir(struct cx18 *cx, struct i2c_adapter *adap, u32 hw,
 	       -1 : 0;
 }
 
+int cx18_get_max_bus_num()
+{
+	return sizeof(hw_bus);
+}
+
 int cx18_i2c_register(struct cx18 *cx, unsigned idx)
 {
 	struct v4l2_subdev *sd;
diff --git a/drivers/media/pci/cx18/cx18-i2c.h b/drivers/media/pci/cx18/cx18-i2c.h
index 1180fdc..8cce205 100644
--- a/drivers/media/pci/cx18/cx18-i2c.h
+++ b/drivers/media/pci/cx18/cx18-i2c.h
@@ -21,6 +21,7 @@
  *  02111-1307  USA
  */
 
+int cx18_get_max_bus_num();
 int cx18_i2c_register(struct cx18 *cx, unsigned idx);
 struct v4l2_subdev *cx18_find_hw(struct cx18 *cx, u32 hw);
 
-- 
1.8.3.4 (Apple Git-47)

Re: [PATCH] [media] cx18: introduce a helper function to void array overrun

[Dmitry Torokhov]

Hi Ethan,

On Sun, Jan 05, 2014 at 09:17:39AM +0800, Ethan Zhao wrote:
> cx18_i2c_register() is called in cx18_init_subdevs() with index
> greater than length of hw_bus array, that will cause array overrun,
> introduce a helper cx18_get_max_bus_num() to void it.

s/void/avoid/

> 
> Signed-off-by: Ethan Zhao <ethan.kernel@gmail.com>
> ---
>  drivers/media/pci/cx18/cx18-driver.c | 2 +-
>  drivers/media/pci/cx18/cx18-i2c.c    | 5 +++++
>  drivers/media/pci/cx18/cx18-i2c.h    | 1 +
>  3 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/pci/cx18/cx18-driver.c b/drivers/media/pci/cx18/cx18-driver.c
> index 6386ced..dadcd4a 100644
> --- a/drivers/media/pci/cx18/cx18-driver.c
> +++ b/drivers/media/pci/cx18/cx18-driver.c
> @@ -856,7 +856,7 @@ static void cx18_init_subdevs(struct cx18 *cx)
>  	u32 device;
>  	int i;
>  
> -	for (i = 0, device = 1; i < 32; i++, device <<= 1) {
> +	for (i = 0, device = 1; i < cx18_get_max_bus_num(); i++, device <<= 1) {
>  
>  		if (!(device & hw))
>  			continue;
> diff --git a/drivers/media/pci/cx18/cx18-i2c.c b/drivers/media/pci/cx18/cx18-i2c.c
> index 4af8cd6..e0e8193 100644
> --- a/drivers/media/pci/cx18/cx18-i2c.c
> +++ b/drivers/media/pci/cx18/cx18-i2c.c
> @@ -108,6 +108,11 @@ static int cx18_i2c_new_ir(struct cx18 *cx, struct i2c_adapter *adap, u32 hw,
>  	       -1 : 0;
>  }
>  
> +int cx18_get_max_bus_num()

This should be "int cx18_get_max_bus_num(void)" since we are using C and
not C++.

> +{
> +	return sizeof(hw_bus);

I'd rather see

	return ARRAY_SIZE(hw_bus);

Thanks.

-- 
Dmitry

Re: [PATCH] [media] cx18: introduce a helper function to void array overrun

[Ethan Zhao]

On Sun, Jan 5, 2014 at 2:09 PM, Dmitry Torokhov
<dmitry.torokhov@gmail.com> wrote:
> Hi Ethan,
>
> On Sun, Jan 05, 2014 at 09:17:39AM +0800, Ethan Zhao wrote:
>> cx18_i2c_register() is called in cx18_init_subdevs() with index
>> greater than length of hw_bus array, that will cause array overrun,
>> introduce a helper cx18_get_max_bus_num() to void it.
>
> s/void/avoid/

Oops, typo.
>
>>
>> Signed-off-by: Ethan Zhao <ethan.kernel@gmail.com>
>> ---
>>  drivers/media/pci/cx18/cx18-driver.c | 2 +-
>>  drivers/media/pci/cx18/cx18-i2c.c    | 5 +++++
>>  drivers/media/pci/cx18/cx18-i2c.h    | 1 +
>>  3 files changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/media/pci/cx18/cx18-driver.c b/drivers/media/pci/cx18/cx18-driver.c
>> index 6386ced..dadcd4a 100644
>> --- a/drivers/media/pci/cx18/cx18-driver.c
>> +++ b/drivers/media/pci/cx18/cx18-driver.c
>> @@ -856,7 +856,7 @@ static void cx18_init_subdevs(struct cx18 *cx)
>>       u32 device;
>>       int i;
>>
>> -     for (i = 0, device = 1; i < 32; i++, device <<= 1) {
>> +     for (i = 0, device = 1; i < cx18_get_max_bus_num(); i++, device <<= 1) {
>>
>>               if (!(device & hw))
>>                       continue;
>> diff --git a/drivers/media/pci/cx18/cx18-i2c.c b/drivers/media/pci/cx18/cx18-i2c.c
>> index 4af8cd6..e0e8193 100644
>> --- a/drivers/media/pci/cx18/cx18-i2c.c
>> +++ b/drivers/media/pci/cx18/cx18-i2c.c
>> @@ -108,6 +108,11 @@ static int cx18_i2c_new_ir(struct cx18 *cx, struct i2c_adapter *adap, u32 hw,
>>              -1 : 0;
>>  }
>>
>> +int cx18_get_max_bus_num()
>
> This should be "int cx18_get_max_bus_num(void)" since we are using C and
> not C++.
agree, no parameter function, f(void) much clearer than any parameters
function f() in C.
>
>> +{
>> +     return sizeof(hw_bus);
>
> I'd rather see
>
>         return ARRAY_SIZE(hw_bus);

Yes, looks better ! will send v2, thanks.
>
> Thanks.
>
> --
> Dmitry