[PATCH] net: iucv: Free memory obtained by kzalloc

[PATCH] net: iucv: Free memory obtained by kzalloc

[Arvind Yadav]

Free memory, if afiucv_iucv_init is not successful and
removing a IUCV driver.

Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
---
 net/iucv/af_iucv.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
index 1e8cc7b..eb0995a 100644
--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -2433,9 +2433,11 @@ static int afiucv_iucv_init(void)
 	af_iucv_dev->driver = &af_iucv_driver;
 	err = device_register(af_iucv_dev);
 	if (err)
-		goto out_driver;
+		goto out_iucv_dev;
 	return 0;
 
+out_iucv_dev:
+	kfree(af_iucv_dev);
 out_driver:
 	driver_unregister(&af_iucv_driver);
 out_iucv:
@@ -2496,6 +2498,7 @@ static void __exit afiucv_exit(void)
 {
 	if (pr_iucv) {
 		device_unregister(af_iucv_dev);
+		kfree(af_iucv_dev);
 		driver_unregister(&af_iucv_driver);
 		pr_iucv->iucv_unregister(&af_iucv_handler, 0);
 		symbol_put(iucv_if);
-- 
1.9.1

Re: [PATCH] net: iucv: Free memory obtained by kzalloc

[Cornelia Huck]

On Wed, 28 Feb 2018 15:24:16 +0530
Arvind Yadav <arvind.yadav.cs@gmail.com> wrote:

> Free memory, if afiucv_iucv_init is not successful and
> removing a IUCV driver.
> 
> Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
> ---
>  net/iucv/af_iucv.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
> index 1e8cc7b..eb0995a 100644
> --- a/net/iucv/af_iucv.c
> +++ b/net/iucv/af_iucv.c
> @@ -2433,9 +2433,11 @@ static int afiucv_iucv_init(void)
>  	af_iucv_dev->driver = &af_iucv_driver;
>  	err = device_register(af_iucv_dev);
>  	if (err)
> -		goto out_driver;
> +		goto out_iucv_dev;
>  	return 0;
>  
> +out_iucv_dev:
> +	kfree(af_iucv_dev);
>  out_driver:
>  	driver_unregister(&af_iucv_driver);
>  out_iucv:
> @@ -2496,6 +2498,7 @@ static void __exit afiucv_exit(void)
>  {
>  	if (pr_iucv) {
>  		device_unregister(af_iucv_dev);
> +		kfree(af_iucv_dev);
>  		driver_unregister(&af_iucv_driver);
>  		pr_iucv->iucv_unregister(&af_iucv_handler, 0);
>  		symbol_put(iucv_if);

No, you must not use kfree() after you called device_register() (even
if it was not successful!) -- see the comment for device_register().

Re: [PATCH] net: iucv: Free memory obtained by kzalloc

[Arvind Yadav]

On Wednesday 28 February 2018 04:00 PM, Cornelia Huck wrote:
> On Wed, 28 Feb 2018 15:24:16 +0530
> Arvind Yadav <arvind.yadav.cs@gmail.com> wrote:
>
>> Free memory, if afiucv_iucv_init is not successful and
>> removing a IUCV driver.
>>
>> Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
>> ---
>>   net/iucv/af_iucv.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
>> index 1e8cc7b..eb0995a 100644
>> --- a/net/iucv/af_iucv.c
>> +++ b/net/iucv/af_iucv.c
>> @@ -2433,9 +2433,11 @@ static int afiucv_iucv_init(void)
>>   	af_iucv_dev->driver = &af_iucv_driver;
>>   	err = device_register(af_iucv_dev);
>>   	if (err)
>> -		goto out_driver;
>> +		goto out_iucv_dev;
>>   	return 0;
>>   
>> +out_iucv_dev:
>> +	kfree(af_iucv_dev);
>>   out_driver:
>>   	driver_unregister(&af_iucv_driver);
>>   out_iucv:
>> @@ -2496,6 +2498,7 @@ static void __exit afiucv_exit(void)
>>   {
>>   	if (pr_iucv) {
>>   		device_unregister(af_iucv_dev);
>> +		kfree(af_iucv_dev);
>>   		driver_unregister(&af_iucv_driver);
>>   		pr_iucv->iucv_unregister(&af_iucv_handler, 0);
>>   		symbol_put(iucv_if);
> No, you must not use kfree() after you called device_register() (even
> if it was not successful!) -- see the comment for device_register().
Yes, Your are right. First we need to call put_device() then kfree().
I will send updated patch.
~arvind

Re: [PATCH] net: iucv: Free memory obtained by kzalloc

[Cornelia Huck]

On Wed, 28 Feb 2018 17:14:55 +0530
Arvind Yadav <arvind.yadav.cs@gmail.com> wrote:

> On Wednesday 28 February 2018 04:00 PM, Cornelia Huck wrote:
> > On Wed, 28 Feb 2018 15:24:16 +0530
> > Arvind Yadav <arvind.yadav.cs@gmail.com> wrote:
> >  
> >> Free memory, if afiucv_iucv_init is not successful and
> >> removing a IUCV driver.
> >>
> >> Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
> >> ---
> >>   net/iucv/af_iucv.c | 5 ++++-
> >>   1 file changed, 4 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
> >> index 1e8cc7b..eb0995a 100644
> >> --- a/net/iucv/af_iucv.c
> >> +++ b/net/iucv/af_iucv.c
> >> @@ -2433,9 +2433,11 @@ static int afiucv_iucv_init(void)
> >>   	af_iucv_dev->driver = &af_iucv_driver;
> >>   	err = device_register(af_iucv_dev);
> >>   	if (err)
> >> -		goto out_driver;
> >> +		goto out_iucv_dev;
> >>   	return 0;
> >>   
> >> +out_iucv_dev:
> >> +	kfree(af_iucv_dev);
> >>   out_driver:
> >>   	driver_unregister(&af_iucv_driver);
> >>   out_iucv:
> >> @@ -2496,6 +2498,7 @@ static void __exit afiucv_exit(void)
> >>   {
> >>   	if (pr_iucv) {
> >>   		device_unregister(af_iucv_dev);
> >> +		kfree(af_iucv_dev);
> >>   		driver_unregister(&af_iucv_driver);
> >>   		pr_iucv->iucv_unregister(&af_iucv_handler, 0);
> >>   		symbol_put(iucv_if);  
> > No, you must not use kfree() after you called device_register() (even
> > if it was not successful!) -- see the comment for device_register().  
> Yes, Your are right. First we need to call put_device() then kfree().
> I will send updated patch.

No, that's not correct, either. device_register() will give up any
reference it obtained, and the caller did not obtain any additional
reference, so a put_device() would be wrong. A kfree() on a refcounted
structure is wrong as well.

Re: [PATCH] net: iucv: Free memory obtained by kzalloc

[Arvind Yadav]

On Wednesday 28 February 2018 05:26 PM, Cornelia Huck wrote:
> On Wed, 28 Feb 2018 17:14:55 +0530
> Arvind Yadav <arvind.yadav.cs@gmail.com> wrote:
>
>> On Wednesday 28 February 2018 04:00 PM, Cornelia Huck wrote:
>>> On Wed, 28 Feb 2018 15:24:16 +0530
>>> Arvind Yadav <arvind.yadav.cs@gmail.com> wrote:
>>>   
>>>> Free memory, if afiucv_iucv_init is not successful and
>>>> removing a IUCV driver.
>>>>
>>>> Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
>>>> ---
>>>>    net/iucv/af_iucv.c | 5 ++++-
>>>>    1 file changed, 4 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
>>>> index 1e8cc7b..eb0995a 100644
>>>> --- a/net/iucv/af_iucv.c
>>>> +++ b/net/iucv/af_iucv.c
>>>> @@ -2433,9 +2433,11 @@ static int afiucv_iucv_init(void)
>>>>    	af_iucv_dev->driver = &af_iucv_driver;
>>>>    	err = device_register(af_iucv_dev);
>>>>    	if (err)
>>>> -		goto out_driver;
>>>> +		goto out_iucv_dev;
>>>>    	return 0;
>>>>    
>>>> +out_iucv_dev:
>>>> +	kfree(af_iucv_dev);
>>>>    out_driver:
>>>>    	driver_unregister(&af_iucv_driver);
>>>>    out_iucv:
>>>> @@ -2496,6 +2498,7 @@ static void __exit afiucv_exit(void)
>>>>    {
>>>>    	if (pr_iucv) {
>>>>    		device_unregister(af_iucv_dev);
>>>> +		kfree(af_iucv_dev);
>>>>    		driver_unregister(&af_iucv_driver);
>>>>    		pr_iucv->iucv_unregister(&af_iucv_handler, 0);
>>>>    		symbol_put(iucv_if);
>>> No, you must not use kfree() after you called device_register() (even
>>> if it was not successful!) -- see the comment for device_register().
>> Yes, Your are right. First we need to call put_device() then kfree().
>> I will send updated patch.
> No, that's not correct, either. device_register() will give up any
> reference it obtained, and the caller did not obtain any additional
> reference, so a put_device() would be wrong. A kfree() on a refcounted
> structure is wrong as well.
If you will see the comment for device_register() (drivers/base/core.c)
there is mentioned that
'NOTE: _Never_ directly free @dev after calling this function, even
if it returned an error! Always use put_device() to give up the
reference initialized in this function instead.'
But as per you comment. we should not use.
Thanks,

Aw: Re: [PATCH] net: iucv: Free memory obtained by kzalloc

[Lino Sanfilippo]

Hi,


> On Wednesday 28 February 2018 05:26 PM, Cornelia Huck wrote:
> > On Wed, 28 Feb 2018 17:14:55 +0530
> > Arvind Yadav <arvind.yadav.cs@gmail.com> wrote:
> >
> >> On Wednesday 28 February 2018 04:00 PM, Cornelia Huck wrote:
> >>> On Wed, 28 Feb 2018 15:24:16 +0530
> >>> Arvind Yadav <arvind.yadav.cs@gmail.com> wrote:
> >>>   
> >>>> Free memory, if afiucv_iucv_init is not successful and
> >>>> removing a IUCV driver.
> >>>>
> >>>> Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
> >>>> ---
> >>>>    net/iucv/af_iucv.c | 5 ++++-
> >>>>    1 file changed, 4 insertions(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
> >>>> index 1e8cc7b..eb0995a 100644
> >>>> --- a/net/iucv/af_iucv.c
> >>>> +++ b/net/iucv/af_iucv.c
> >>>> @@ -2433,9 +2433,11 @@ static int afiucv_iucv_init(void)
> >>>>    	af_iucv_dev->driver = &af_iucv_driver;
> >>>>    	err = device_register(af_iucv_dev);
> >>>>    	if (err)
> >>>> -		goto out_driver;
> >>>> +		goto out_iucv_dev;
> >>>>    	return 0;
> >>>>    
> >>>> +out_iucv_dev:
> >>>> +	kfree(af_iucv_dev);
> >>>>    out_driver:
> >>>>    	driver_unregister(&af_iucv_driver);
> >>>>    out_iucv:
> >>>> @@ -2496,6 +2498,7 @@ static void __exit afiucv_exit(void)
> >>>>    {
> >>>>    	if (pr_iucv) {
> >>>>    		device_unregister(af_iucv_dev);
> >>>> +		kfree(af_iucv_dev);
> >>>>    		driver_unregister(&af_iucv_driver);
> >>>>    		pr_iucv->iucv_unregister(&af_iucv_handler, 0);
> >>>>    		symbol_put(iucv_if);
> >>> No, you must not use kfree() after you called device_register() (even
> >>> if it was not successful!) -- see the comment for device_register().
> >> Yes, Your are right. First we need to call put_device() then kfree().
> >> I will send updated patch.
> > No, that's not correct, either. device_register() will give up any
> > reference it obtained, and the caller did not obtain any additional
> > reference, so a put_device() would be wrong. A kfree() on a refcounted
> > structure is wrong as well.
> If you will see the comment for device_register() (drivers/base/core.c)
> there is mentioned that
> 'NOTE: _Never_ directly free @dev after calling this function, even
> if it returned an error! Always use put_device() to give up the
> reference initialized in this function instead.'
> But as per you comment. we should not use.
> Thanks,
> 

In case that device_register() fails simply call device_put(). This will decrement
the last reference and then free the memory.

Regards,
Lino

Re: [PATCH] net: iucv: Free memory obtained by kzalloc

[Cornelia Huck]

On Wed, 28 Feb 2018 17:39:53 +0530
Arvind Yadav <arvind.yadav.cs@gmail.com> wrote:

> On Wednesday 28 February 2018 05:26 PM, Cornelia Huck wrote:
> > On Wed, 28 Feb 2018 17:14:55 +0530
> > Arvind Yadav <arvind.yadav.cs@gmail.com> wrote:
> >  
> >> On Wednesday 28 February 2018 04:00 PM, Cornelia Huck wrote:  
> >>> On Wed, 28 Feb 2018 15:24:16 +0530
> >>> Arvind Yadav <arvind.yadav.cs@gmail.com> wrote:
> >>>     
> >>>> Free memory, if afiucv_iucv_init is not successful and
> >>>> removing a IUCV driver.
> >>>>
> >>>> Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
> >>>> ---
> >>>>    net/iucv/af_iucv.c | 5 ++++-
> >>>>    1 file changed, 4 insertions(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
> >>>> index 1e8cc7b..eb0995a 100644
> >>>> --- a/net/iucv/af_iucv.c
> >>>> +++ b/net/iucv/af_iucv.c
> >>>> @@ -2433,9 +2433,11 @@ static int afiucv_iucv_init(void)
> >>>>    	af_iucv_dev->driver = &af_iucv_driver;
> >>>>    	err = device_register(af_iucv_dev);
> >>>>    	if (err)
> >>>> -		goto out_driver;
> >>>> +		goto out_iucv_dev;
> >>>>    	return 0;
> >>>>    
> >>>> +out_iucv_dev:
> >>>> +	kfree(af_iucv_dev);
> >>>>    out_driver:
> >>>>    	driver_unregister(&af_iucv_driver);
> >>>>    out_iucv:
> >>>> @@ -2496,6 +2498,7 @@ static void __exit afiucv_exit(void)
> >>>>    {
> >>>>    	if (pr_iucv) {
> >>>>    		device_unregister(af_iucv_dev);
> >>>> +		kfree(af_iucv_dev);
> >>>>    		driver_unregister(&af_iucv_driver);
> >>>>    		pr_iucv->iucv_unregister(&af_iucv_handler, 0);
> >>>>    		symbol_put(iucv_if);  
> >>> No, you must not use kfree() after you called device_register() (even
> >>> if it was not successful!) -- see the comment for device_register().  
> >> Yes, Your are right. First we need to call put_device() then kfree().
> >> I will send updated patch.  
> > No, that's not correct, either. device_register() will give up any
> > reference it obtained, and the caller did not obtain any additional
> > reference, so a put_device() would be wrong. A kfree() on a refcounted
> > structure is wrong as well.  
> If you will see the comment for device_register() (drivers/base/core.c)
> there is mentioned that
> 'NOTE: _Never_ directly free @dev after calling this function, even
> if it returned an error! Always use put_device() to give up the
> reference initialized in this function instead.'
> But as per you comment. we should not use.

You don't need to do a put_device() after your device_unregister(),
that's all managed by the driver core.