Re: [PATCHv2] char:ipmi: Free ipmi_recv_msg messages from the linked list,recv_msgs for the function,ipmi_release in the file,ipmi_devintf.c

Re: [PATCHv2] char:ipmi: Free ipmi_recv_msg messages from the linked list,recv_msgs for the function,ipmi_release in the file,ipmi_devintf.c

[Corey Minyard]

On 01/23/2015 12:27 PM, nick wrote:
> Corney,
> Hope this patch fixes the issue. Sorry about missing that kfree
> being required. :(

Well, the kfree needs to be after the free of the messages.    You can't
use an item after you free it.

-corey

> Nick
>
>
> On 2015-01-23 01:02 PM, Nicholas Krause wrote:
>> This adds a loop through the elements in the linked list, recv_msgs using
>> list_for_entry_safe in order to free messages in this list.  In addition
>> we are using the safe version of this marco in order to prevent use after
>> bugs related to deleting the element we are on currently by holding a
>> pointer to the next element after the current one we are on and freeing
>> with the function, ipmi_free_recv_msg internally in this loop.
>>
>> Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
>> ---
>>  drivers/char/ipmi/ipmi_devintf.c | 7 ++++++-
>>  1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/char/ipmi/ipmi_devintf.c b/drivers/char/ipmi/ipmi_devintf.c
>> index ec318bf..a625510 100644
>> --- a/drivers/char/ipmi/ipmi_devintf.c
>> +++ b/drivers/char/ipmi/ipmi_devintf.c
>> @@ -157,14 +157,19 @@ static int ipmi_release(struct inode *inode, struct file *file)
>>  {
>>  	struct ipmi_file_private *priv = file->private_data;
>>  	int                      rv;
>> +	struct  ipmi_recv_msg *msg, *next;
>>  
>>  	rv = ipmi_destroy_user(priv->user);
>>  	if (rv)
>>  		return rv;
>>  
>> -	/* FIXME - free the messages in the list. */
>>  	kfree(priv);
>>  
>> +	list_for_each_entry_safe(msg, next, &priv->recv_msgs, link) {
>> +		ipmi_free_recv_msg(msg);
>> +	}
>> +
>> +
>>  	return 0;
>>  }
>>  
>>

Re: [PATCHv2] char:ipmi: Free ipmi_recv_msg messages from the linked list,recv_msgs for the function,ipmi_release in the file,ipmi_devintf.c

[Sasha Levin]

On 01/23/2015 02:00 PM, Corey Minyard wrote:
> On 01/23/2015 12:27 PM, nick wrote:
>> > Corney,
>> > Hope this patch fixes the issue. Sorry about missing that kfree
>> > being required. :(
> Well, the kfree needs to be after the free of the messages.    You can't
> use an item after you free it.

As you can see, his patches aren't event tested. See https://lkml.org/lkml/2014/8/4/206 .

Thanks,
Sasha