[PATCH 4.19 148/190] scsi: zfcp: fix request object use-after-free in send path causing wrong traces

Greg Kroah-Hartman
2019-09-13T13:18:24Z

[ Upstream commit 106d45f350c7cac876844dc685845cba4ffdb70b ]

When tracing instances where we open and close WKA ports, we also pass the
request-ID of the respective FSF command.

But after successfully sending the FSF command we must not use the
request-object anymore, as this might result in an use-after-free (see
"zfcp: fix request object use-after-free in send path causing seqno
errors" ).

To fix this add a new variable that caches the request-ID before sending
the request. This won't change during the hand-off to the FCP channel,
and so it's safe to trace this cached request-ID later, instead of using
the request object.

Signed-off-by: Benjamin Block <bblock@linux.ibm.com>
Fixes: d27a7cb91960 ("zfcp: trace on request for open and close of WKA port")
Cc: <stable@vger.kernel.org> #2.6.38+
Reviewed-by: Steffen Maier <maier@linux.ibm.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/s390/scsi/zfcp_fsf.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/s390/scsi/zfcp_fsf.c b/drivers/s390/scsi/zfcp_fsf.c
index 3c86e27f094de..aff073a5b52bf 100644
--- a/drivers/s390/scsi/zfcp_fsf.c
+++ b/drivers/s390/scsi/zfcp_fsf.c
@@ -1594,6 +1594,7 @@ int zfcp_fsf_open_wka_port(struct zfcp_fc_wka_port *wka_port)
{
struct zfcp_qdio *qdio = wka_port->adapter->qdio;
struct zfcp_fsf_req *req;
+ unsigned long req_id = 0;
int retval = -EIO;

spin_lock_irq(&qdio->req_q_lock);
@@ -1616,6 +1617,8 @@ int zfcp_fsf_open_wka_port(struct zfcp_fc_wka_port *wka_port)
hton24(req->qtcb->bottom.support.d_id, wka_port->d_id);
req->data = wka_port;

+ req_id = req->req_id;
+
zfcp_fsf_start_timer(req, ZFCP_FSF_REQUEST_TIMEOUT);
retval = zfcp_fsf_req_send(req);
if (retval)
@@ -1623,7 +1626,7 @@ int zfcp_fsf_open_wka_port(struct zfcp_fc_wka_port *wka_port)
out:
spin_unlock_irq(&qdio->req_q_lock);
if (!retval)
- zfcp_dbf_rec_run_wka("fsowp_1", wka_port, req->req_id);
+ zfcp_dbf_rec_run_wka("fsowp_1", wka_port, req_id);
return retval;
}

@@ -1649,6 +1652,7 @@ int zfcp_fsf_close_wka_port(struct zfcp_fc_wka_port *wka_port)
{
struct zfcp_qdio *qdio = wka_port->adapter->qdio;
struct zfcp_fsf_req *req;
+ unsigned long req_id = 0;
int retval = -EIO;

spin_lock_irq(&qdio->req_q_lock);
@@ -1671,6 +1675,8 @@ int zfcp_fsf_close_wka_port(struct zfcp_fc_wka_port *wka_port)
req->data = wka_port;
req->qtcb->header.port_handle = wka_port->handle;

+ req_id = req->req_id;
+
zfcp_fsf_start_timer(req, ZFCP_FSF_REQUEST_TIMEOUT);
retval = zfcp_fsf_req_send(req);
if (retval)
@@ -1678,7 +1684,7 @@ int zfcp_fsf_close_wka_port(struct zfcp_fc_wka_port *wka_port)
out:
spin_unlock_irq(&qdio->req_q_lock);
if (!retval)
- zfcp_dbf_rec_run_wka("fscwp_1", wka_port, req->req_id);
+ zfcp_dbf_rec_run_wka("fscwp_1", wka_port, req_id);
return retval;
}

--
2.20.1