linux-kernel - Re: [PATCH] USB: Gadget: Composite: Added error handling codes to prevent a memory leak case when the configuration's bind function failed

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Date:	Mon, 19 Mar 2012 17:34:04 +0900
From:	Yongsul Oh <yongsul96.oh@...sung.com>
To:	Michal Nazarewicz <mina86@...a86.com>
Cc:	Felipe Balbi <balbi@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Michal Nazarewicz <mnazarewicz@...il.com>,
	Sergei Shtylyov <sshtylyov@...sta.com>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] USB: Gadget: Composite: Added error handling codes to
 prevent a memory leak case when the configuration's bind function failed

Dear Michal Nazarewicz

Thank you very much for your kindness.
And i also agree with your comments.
I wil try to change my commit-msg & re-send it as soon as possible.

And about your last commets,

 > Also, like written previously, I think there might be memory leak in 
other error
 > recovery paths as well.  If you could take a look whether I'm right, 
that would be
 > awesome.

I will try to find out if the memory leaks in other error recovery paths 
or not,
  but i think that might be another case and need different patch-set.
(If i find out that, i will try to make another patch-set and send it 
all again)

Best regards.
Yongsul Oh

On 2012년 03월 16일 20:14, Michal Nazarewicz wrote:
> On Fri, 16 Mar 2012 07:27:15 +0100, Yongsul Oh 
> <yongsul96.oh@...sung.com> wrote:
>
>>  In some usb gadget driver, (for example usb gadget serial 
>> driver(serial.c),
>
> s/usb/USB/g
> s/gadget driver/composite gadget drivers/
>
> I also don't think the list of examples is necessary here.  Maybe just 
> a list file
> names? My personal opinion, others may disagree though.
>
> Also, comma should go after the closing paren.
>
>> multifunction composite driver(multi,c), nokia composite gadget 
>> driver(nokia.c),
>> HID composite driver(hid.c), CDC composite driver(cdc2.c)..) the 
>> configuration's
>> bind function by called the 'usb_add_config()' has multiple bind 
>> config functions
>
> s/by called the/called by the/
> s/has/calls/
>
>> for each functionality. (for example cdc2 configuration bind function 
>> -'cdc_do_config()'
>
> s/functions for each functionality/functions, one for each USB 
> functionality/
>
>> has two functionality bind config functions -'ecm_bind_config()' & 
>> 'acm_bind_config()'
>> in CDC composite driver.)
>>
>>  In each functionality bind config function, new instance for each 
>> functionality is
>
> s/for each functionality//
>
>> allocated & initialized by 'kzalloc()' and finally the new instance 
>> is added by
>
> s/& initialized by 'kzalloc()' and finally the new instance/and/
>
>> 'usb_add_function()'. After 'usb_add_function' state, already created 
>> the instance
>> is only handled by it's configuration & freed from functionality 
>> unbind function.
>
> I'm not sure what you meant by this last sentence.
>
>>  So, If an error occurred during the second functionality bind config 
>> state,
>
> s/If/if/
> s/state//
>
>> (for example an error occurred at 'acm_bind_config()' after 
>> succeeding of
>> 'ecm_bind_function()') the created instance by 'acm_bind_config()'
>
> s/the created instance by 'acm_bind_config()'/the instance created by 
> acm_bind_config()/
>
>> cannot be freed. And it makes memory leak situation.
>
> s/freed. And it makes memory leak situation./freed creating a memory 
> leak./
>
>> This patch fixes this issue
>
> s/issue/issue./
>
> Also, drop apostrophes around function names.  It looks weird.
>
>> Signed-off-by: Yongsul Oh <yongsul96.oh@...sung.com>
>
> Acked-by: Michal Nazarewicz <mina86@...a86.com>
>
> Also, like written previously, I think there might be memory leak in 
> other error
> recovery paths as well.  If you could take a look whether I'm right, 
> that would be
> awesome.
>
>> ---
>>  drivers/usb/gadget/composite.c |   13 +++++++++++++
>>  1 files changed, 13 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/usb/gadget/composite.c 
>> b/drivers/usb/gadget/composite.c
>> index baaebf2..4cb1801 100644
>> --- a/drivers/usb/gadget/composite.c
>> +++ b/drivers/usb/gadget/composite.c
>> @@ -737,6 +737,19 @@ int usb_add_config(struct usb_composite_dev *cdev,
>>     status = bind(config);
>>      if (status < 0) {
>> +        while (!list_empty(&config->functions)) {
>> +            struct usb_function        *f;
>> +
>> +            f = list_first_entry(&config->functions,
>> +                    struct usb_function, list);
>> +            list_del(&f->list);
>> +            if (f->unbind) {
>> +                DBG(cdev, "unbind function '%s'/%p\n",
>> +                    f->name, f);
>> +                f->unbind(config, f);
>> +                /* may free memory for "f" */
>> +            }
>> +        }
>>          list_del(&config->list);
>>          config->cdev = NULL;
>>      } else {
>
>

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