linux-kernel - Re: [PATCH v2] tracing: fix referencing after memory freeing and refactors code

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Message-ID: <CAGG-pUSASKfQ35TJ4fKkkM0kUw7oi+qDkTVCRnpj336_k2GsJg@mail.gmail.com>
Date:	Wed, 6 Nov 2013 18:18:32 -0200
From:	Geyslan Gregório Bem <geyslan@...il.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	kernel-br <kernel-br@...glegroups.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] tracing: fix referencing after memory freeing and
 refactors code

2013/11/6 Steven Rostedt <rostedt@...dmis.org>:
> On Wed,  6 Nov 2013 16:02:51 -0300
> "Geyslan G. Bem" <geyslan@...il.com> wrote:
>
>> In 'system_tr_open()':
>> Fix possible 'dir' assignment after freeing it.
>
> I'll take this patch, but I'm going to reword the subject and the
> change log. The assignment of dir to filp->private_data after dir is
> freed is not as bad as it sounds. As we are returning an error,
> filp->private_data is never used.
>
> -- Steve
>
>
Ok Steve. Please, do the reword.

>>
>> In both functions:
>> Restructures logic conditions testing 'tracing_is_disabled()'
>> return before the others tests.
>>
>> Signed-off-by: Geyslan G. Bem <geyslan@...il.com>
>> ---
>>  kernel/trace/trace_events.c | 9 ++++++++-
>>  1 file changed, 8 insertions(+), 1 deletion(-)
>>
>> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
>> index 368a4d5..b44a7ea 100644
>> --- a/kernel/trace/trace_events.c
>> +++ b/kernel/trace/trace_events.c
>> @@ -1062,6 +1062,9 @@ static int subsystem_open(struct inode *inode, struct file *filp)
>>       struct trace_array *tr;
>>       int ret;
>>
>> +     if (tracing_is_disabled())
>> +             return -ENODEV;
>> +
>>       /* Make sure the system still exists */
>>       mutex_lock(&trace_types_lock);
>>       mutex_lock(&event_mutex);
>> @@ -1108,6 +1111,9 @@ static int system_tr_open(struct inode *inode, struct file *filp)
>>       struct trace_array *tr = inode->i_private;
>>       int ret;
>>
>> +     if (tracing_is_disabled())
>> +             return -ENODEV;
>> +
>>       if (trace_array_get(tr) < 0)
>>               return -ENODEV;
>>
>> @@ -1124,11 +1130,12 @@ static int system_tr_open(struct inode *inode, struct file *filp)
>>       if (ret < 0) {
>>               trace_array_put(tr);
>>               kfree(dir);
>> +             return ret;
>>       }
>>
>>       filp->private_data = dir;
>>
>> -     return ret;
>> +     return 0;
>>  }
>>
>>  static int subsystem_release(struct inode *inode, struct file *file)
>



-- 
Regards,

Geyslan G. Bem
hackingbits.com
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