linux-kernel - Re: [PATCH] [SCSI] iscsi_boot_sysfs: Fix a memory leak in iscsi_boot_destroy

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Date:	Tue, 10 Dec 2013 09:11:00 -0500
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	Ethan Zhao <ethan.kernel@...il.com>
CC:	michaelc@...wisc.edu, pjones@...hat.com,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] [SCSI] iscsi_boot_sysfs: Fix a memory leak in iscsi_boot_destroy_kset()

Ethan Zhao <ethan.kernel@...il.com> wrote:
>Konrad,
>
> boot_kset was allocated when module loaded by
>ibft_init()
>  iscsi_boot_create_kset()
>     kzalloc()
>
>but wasn't freed when module unloaded by
>ibft_exit()
>   ibft_cleanup()
>     iscsi_boot_destroy_kset()
>
>Thanks,
>Ethan
>
>On Tue, Dec 10, 2013 at 5:30 AM, Konrad Rzeszutek Wilk
><konrad.wilk@...cle.com> wrote:
>> On Mon, Dec 09, 2013 at 05:37:11PM +0800, Ethan Zhao wrote:
>>> From: "Ethan Zhao" <ethan.kernel@...il.com>
>>>
>>> Load and unload iscsi_ibft module will cause kernel memory leak, fix
>it
>>> in scsi/iscsi_boot_sysfs.c iscsi_boot_destroy_kset().
>>>
>>
>> Is there a stack trace?
>>> Signed-off-by: Ethan Zhao <ethan.kernel@...il.com>
>>> ---
>>>  drivers/scsi/iscsi_boot_sysfs.c | 1 +
>>>  1 file changed, 1 insertion(+)
>>>
>>> diff --git a/drivers/scsi/iscsi_boot_sysfs.c
>b/drivers/scsi/iscsi_boot_sysfs.c
>>> index 14c1c8f..680bf6f 100644
>>> --- a/drivers/scsi/iscsi_boot_sysfs.c
>>> +++ b/drivers/scsi/iscsi_boot_sysfs.c
>>> @@ -490,5 +490,6 @@ void iscsi_boot_destroy_kset(struct
>iscsi_boot_kset *boot_kset)
>>>               iscsi_boot_remove_kobj(boot_kobj);
>>>
>>>       kset_unregister(boot_kset->kset);
>>> +     kfree(boot_kset);
>>>  }
>>>  EXPORT_SYMBOL_GPL(iscsi_boot_destroy_kset);
>>> --
>>> 1.8.3.4 (Apple Git-47)
>>>

Right. In the past we did not do that b/c certain drivers (like broadcom) would allocate on the kset their name and try to free (the driver would after freeing the ibft). So you would end up with this patch a double free ( and it might be fixed by now but I can't recall).

My question was - did you observer a crash or bug. Hence the question about stack trace? How did you see this?

Thank you.

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