2023-09-22 07:51:51

by Dinghao Liu

Subject: [PATCH] [v2] 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 <[email protected]>
---

Changelog:

v2: -Improve the patch description.
-Add a new label 'err_register' to unify code style.
---
drivers/s390/scsi/zfcp_aux.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/scsi/zfcp_aux.c b/drivers/s390/scsi/zfcp_aux.c
index df782646e856..ad0ef9546501 100644
--- a/drivers/s390/scsi/zfcp_aux.c
+++ b/drivers/s390/scsi/zfcp_aux.c
@@ -552,7 +552,7 @@ struct zfcp_port *zfcp_port_enqueue(struct zfcp_adapter *adapter, u64 wwpn,

if (device_register(&port->dev)) {
put_device(&port->dev);
- goto err_out;
+ goto err_register;
}

write_lock_irq(&adapter->port_list_lock);
@@ -565,5 +565,6 @@ struct zfcp_port *zfcp_port_enqueue(struct zfcp_adapter *adapter, u64 wwpn,

err_out:
zfcp_ccw_adapter_put(adapter);
+err_register:
return ERR_PTR(retval);
}
--
2.17.1

2023-09-22 22:54:44

by Bart Van Assche

Subject: Re: [PATCH] [v2] scsi: zfcp: Fix a double put in zfcp_port_enqueue

On 9/22/23 00:46, Dinghao Liu wrote:
> diff --git a/drivers/s390/scsi/zfcp_aux.c b/drivers/s390/scsi/zfcp_aux.c
> index df782646e856..ad0ef9546501 100644
> --- a/drivers/s390/scsi/zfcp_aux.c
> +++ b/drivers/s390/scsi/zfcp_aux.c
> @@ -552,7 +552,7 @@ struct zfcp_port *zfcp_port_enqueue(struct zfcp_adapter *adapter, u64 wwpn,
>
> if (device_register(&port->dev)) {
> put_device(&port->dev);
> - goto err_out;
> + goto err_register;
> }
>
> write_lock_irq(&adapter->port_list_lock);
> @@ -565,5 +565,6 @@ struct zfcp_port *zfcp_port_enqueue(struct zfcp_adapter *adapter, u64 wwpn,
>
> err_out:
> zfcp_ccw_adapter_put(adapter);
> +err_register:
> return ERR_PTR(retval);
> }

goto labels should be named after the code below the goto label instead
of reflecting where the goto statement comes from.

Thanks,

Bart.