linux-kernel - [PATCH] scsi: zfcp: fix use-after-free in zfcp_unit

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Date:   Fri, 20 Nov 2020 15:48:54 +0800
From:   Qinglang Miao <miaoqinglang@...wei.com>
To:     Steffen Maier <maier@...ux.ibm.com>,
        Benjamin Block <bblock@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>
CC:     <linux-s390@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        "Qinglang Miao" <miaoqinglang@...wei.com>
Subject: [PATCH] scsi: zfcp: fix use-after-free in zfcp_unit_remove

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@...wei.com>
Signed-off-by: Qinglang Miao <miaoqinglang@...wei.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;
-- 
2.23.0