From: Benjamin Block <bblock@linux.ibm.com>
To: Qinglang Miao <miaoqinglang@huawei.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_sysfs_port_remove_store
Date: Wed, 25 Nov 2020 18:04:09 +0100 [thread overview]
Message-ID: <20201125170409.GA8578@t480-pf1aa2c2> (raw)
In-Reply-To: <20201120074853.31706-1-miaoqinglang@huawei.com>
On Fri, Nov 20, 2020 at 03:48:53PM +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: 83d4e1c33d93 ("[SCSI] zfcp: cleanup port sysfs attribute usage")
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
> ---
> drivers/s390/scsi/zfcp_sysfs.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/drivers/s390/scsi/zfcp_sysfs.c b/drivers/s390/scsi/zfcp_sysfs.c
> index 8d9662e8b..06285e452 100644
> --- a/drivers/s390/scsi/zfcp_sysfs.c
> +++ b/drivers/s390/scsi/zfcp_sysfs.c
> @@ -327,8 +327,6 @@ static ssize_t zfcp_sysfs_port_remove_store(struct device *dev,
> list_del(&port->list);
> write_unlock_irq(&adapter->port_list_lock);
>
> - put_device(&port->dev);
> -
> zfcp_erp_port_shutdown(port, 0, "syprs_1");
> device_unregister(&port->dev);
> out:
Hmm, the placement of the put_device() is indeed strange, now that I
think about it. But just removing it and then having a dangling
reference also seems wrong - we do get one explicitly in
`zfcp_get_port_by_wwpn()`.
My first thought would be to move it after the `device_unregister()`
call, and before the `out:` label.
--
Best Regards, Benjamin Block / Linux on IBM Z Kernel Development / IBM Systems
IBM Deutschland Research & Development GmbH / https://www.ibm.com/privacy
Vorsitz. AufsR.: Gregor Pillen / Geschäftsführung: Dirk Wittkopp
Sitz der Gesellschaft: Böblingen / Registergericht: AmtsG Stuttgart, HRB 243294
prev parent reply other threads:[~2020-11-25 17:04 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-20 7:48 [PATCH] scsi: zfcp: fix use-after-free in zfcp_sysfs_port_remove_store Qinglang Miao
2020-11-25 17:04 ` Benjamin Block [this message]
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