From: Qinglang Miao <miaoqinglang@huawei.com>
To: Benjamin Block <bblock@linux.ibm.com>
Cc: Steffen Maier <maier@linux.ibm.com>,
Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
<linux-s390@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<linux-scsi@vger.kernel.org>
Subject: Re: [PATCH] scsi: zfcp: fix use-after-free in zfcp_unit_remove
Date: Thu, 26 Nov 2020 09:27:41 +0800 [thread overview]
Message-ID: <4c65bead-2553-171e-54d2-87a9de0330e8@huawei.com> (raw)
In-Reply-To: <20201125170658.GB8578@t480-pf1aa2c2>
在 2020/11/26 1:06, Benjamin Block 写道:
> On Fri, Nov 20, 2020 at 03:48:54PM +0800, Qinglang Miao wrote:
>> kfree(port) is called in put_device(&port->dev) so that following
>> use would cause use-after-free bug.
>>
>> The former put_device is redundant for device_unregister contains
>> put_device already. So just remove it to fix this.
>>
>> Fixes: 86bdf218a717 ("[SCSI] zfcp: cleanup unit sysfs attribute usage")
>> Reported-by: Hulk Robot <hulkci@huawei.com>
>> Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
>> ---
>> drivers/s390/scsi/zfcp_unit.c | 2 --
>> 1 file changed, 2 deletions(-)
>>
>> diff --git a/drivers/s390/scsi/zfcp_unit.c b/drivers/s390/scsi/zfcp_unit.c
>> index e67bf7388..664b77853 100644
>> --- a/drivers/s390/scsi/zfcp_unit.c
>> +++ b/drivers/s390/scsi/zfcp_unit.c
>> @@ -255,8 +255,6 @@ int zfcp_unit_remove(struct zfcp_port *port, u64 fcp_lun)
>> scsi_device_put(sdev);
>> }
>>
>> - put_device(&unit->dev);
>> -
>> device_unregister(&unit->dev);
>> >> return 0;
>
> Same as in the other mail for `zfcp_sysfs_port_remove_store()`. We
> explicitly get a new ref in `_zfcp_unit_find()`, so we also need to put
> that away again.
>
Sorry, Benjamin, I don't think so, because device_unregister calls
put_device inside.
It seem's that another put_device before or after device_unregister is
useless and even might cause an use-after-free.
next prev parent reply other threads:[~2020-11-26 1:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-20 7:48 [PATCH] scsi: zfcp: fix use-after-free in zfcp_unit_remove Qinglang Miao
2020-11-25 17:06 ` Benjamin Block
2020-11-26 1:27 ` Qinglang Miao [this message]
2020-11-26 8:13 ` Cornelia Huck
2020-11-26 9:42 ` Benjamin Block
2020-11-26 12:07 ` Qinglang Miao
2020-11-26 15:12 ` Benjamin Block
2020-11-27 9:21 ` Steffen Maier
2020-12-01 2:46 ` Qinglang Miao
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