linux-kernel - [PATCH] [v3] scsi: zfcp: Fix a double put in zfcp_port

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Date:   Sat, 23 Sep 2023 18:37:23 +0800
From:   Dinghao Liu <dinghao.liu@....edu.cn>
To:     dinghao.liu@....edu.cn
Cc:     linux-scsi@...r.kernel.org, Steffen Maier <maier@...ux.ibm.com>,
        Benjamin Block <bblock@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Christof Schmitt <christof.schmitt@...ibm.com>,
        James Bottomley <James.Bottomley@...e.de>,
        Swen Schillig <swen@...t.ibm.com>, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] [v3] scsi: zfcp: Fix a double put in zfcp_port_enqueue

When device_register() fails, zfcp_port_release() will be called
after put_device(). As a result, zfcp_ccw_adapter_put() will be
called twice: one in zfcp_port_release() and one in the error path
after device_register(). So the reference on the adapter object is
doubly put, which may lead to a premature free. Fix this by adjusting
the error tag after device_register().

Fixes: f3450c7b9172 ("[SCSI] zfcp: Replace local reference counting with common kref")
Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>
---

Changelog:

v2: -Improve the patch description.
    -Add a new label 'err_register' to unify code style.

v3: -Improve the names of goto labels.
---
 drivers/s390/scsi/zfcp_aux.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/s390/scsi/zfcp_aux.c b/drivers/s390/scsi/zfcp_aux.c
index df782646e856..ab2f35bc294d 100644
--- a/drivers/s390/scsi/zfcp_aux.c
+++ b/drivers/s390/scsi/zfcp_aux.c
@@ -518,12 +518,12 @@ struct zfcp_port *zfcp_port_enqueue(struct zfcp_adapter *adapter, u64 wwpn,
 	if (port) {
 		put_device(&port->dev);
 		retval = -EEXIST;
-		goto err_out;
+		goto err_put;
 	}
 
 	port = kzalloc(sizeof(struct zfcp_port), GFP_KERNEL);
 	if (!port)
-		goto err_out;
+		goto err_put;
 
 	rwlock_init(&port->unit_list_lock);
 	INIT_LIST_HEAD(&port->unit_list);
@@ -546,7 +546,7 @@ struct zfcp_port *zfcp_port_enqueue(struct zfcp_adapter *adapter, u64 wwpn,
 
 	if (dev_set_name(&port->dev, "0x%016llx", (unsigned long long)wwpn)) {
 		kfree(port);
-		goto err_out;
+		goto err_put;
 	}
 	retval = -EINVAL;
 
@@ -563,7 +563,8 @@ struct zfcp_port *zfcp_port_enqueue(struct zfcp_adapter *adapter, u64 wwpn,
 
 	return port;
 
-err_out:
+err_put:
 	zfcp_ccw_adapter_put(adapter);
+err_out:
 	return ERR_PTR(retval);
 }
-- 
2.17.1