Commit 2dfa6688 authored by Steffen Maier's avatar Steffen Maier Committed by Martin K. Petersen

scsi: zfcp: fix use-after-free by not tracing WKA port open/close on failed send

Dan Carpenter kindly reported:
<quote>
The patch d27a7cb9: "zfcp: trace on request for open and close of
WKA port" from Aug 10, 2016, leads to the following static checker
warning:

	drivers/s390/scsi/zfcp_fsf.c:1615 zfcp_fsf_open_wka_port()
	warn: 'req' was already freed.

drivers/s390/scsi/zfcp_fsf.c
  1609          zfcp_fsf_start_timer(req, ZFCP_FSF_REQUEST_TIMEOUT);
  1610          retval = zfcp_fsf_req_send(req);
  1611          if (retval)
  1612                  zfcp_fsf_req_free(req);
                                          ^^^
Freed.

  1613  out:
  1614          spin_unlock_irq(&qdio->req_q_lock);
  1615          if (req && !IS_ERR(req))
  1616                  zfcp_dbf_rec_run_wka("fsowp_1", wka_port, req->req_id);
                                                                  ^^^^^^^^^^^
Use after free.

  1617          return retval;
  1618  }

Same thing for zfcp_fsf_close_wka_port() as well.
</quote>

Rather than relying on req being NULL (or ERR_PTR) for all cases where
we don't want to trace or should not trace,
simply check retval which is unconditionally initialized with -EIO != 0
and it can only become 0 on successful retval = zfcp_fsf_req_send(req).
With that we can also remove the then again unnecessary unconditional
initialization of req which was introduced with that earlier commit.
Reported-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Suggested-by: default avatarBenjamin Block <bblock@linux.vnet.ibm.com>
Signed-off-by: default avatarSteffen Maier <maier@linux.vnet.ibm.com>
Fixes: d27a7cb9 ("zfcp: trace on request for open and close of WKA port")
Cc: <stable@vger.kernel.org> #2.6.38+
Reviewed-by: default avatarBenjamin Block <bblock@linux.vnet.ibm.com>
Reviewed-by: default avatarJens Remus <jremus@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 8af8e1c2
...@@ -1583,7 +1583,7 @@ static void zfcp_fsf_open_wka_port_handler(struct zfcp_fsf_req *req) ...@@ -1583,7 +1583,7 @@ static void zfcp_fsf_open_wka_port_handler(struct zfcp_fsf_req *req)
int zfcp_fsf_open_wka_port(struct zfcp_fc_wka_port *wka_port) int zfcp_fsf_open_wka_port(struct zfcp_fc_wka_port *wka_port)
{ {
struct zfcp_qdio *qdio = wka_port->adapter->qdio; struct zfcp_qdio *qdio = wka_port->adapter->qdio;
struct zfcp_fsf_req *req = NULL; struct zfcp_fsf_req *req;
int retval = -EIO; int retval = -EIO;
spin_lock_irq(&qdio->req_q_lock); spin_lock_irq(&qdio->req_q_lock);
...@@ -1612,7 +1612,7 @@ int zfcp_fsf_open_wka_port(struct zfcp_fc_wka_port *wka_port) ...@@ -1612,7 +1612,7 @@ int zfcp_fsf_open_wka_port(struct zfcp_fc_wka_port *wka_port)
zfcp_fsf_req_free(req); zfcp_fsf_req_free(req);
out: out:
spin_unlock_irq(&qdio->req_q_lock); spin_unlock_irq(&qdio->req_q_lock);
if (req && !IS_ERR(req)) if (!retval)
zfcp_dbf_rec_run_wka("fsowp_1", wka_port, req->req_id); zfcp_dbf_rec_run_wka("fsowp_1", wka_port, req->req_id);
return retval; return retval;
} }
...@@ -1638,7 +1638,7 @@ static void zfcp_fsf_close_wka_port_handler(struct zfcp_fsf_req *req) ...@@ -1638,7 +1638,7 @@ static void zfcp_fsf_close_wka_port_handler(struct zfcp_fsf_req *req)
int zfcp_fsf_close_wka_port(struct zfcp_fc_wka_port *wka_port) int zfcp_fsf_close_wka_port(struct zfcp_fc_wka_port *wka_port)
{ {
struct zfcp_qdio *qdio = wka_port->adapter->qdio; struct zfcp_qdio *qdio = wka_port->adapter->qdio;
struct zfcp_fsf_req *req = NULL; struct zfcp_fsf_req *req;
int retval = -EIO; int retval = -EIO;
spin_lock_irq(&qdio->req_q_lock); spin_lock_irq(&qdio->req_q_lock);
...@@ -1667,7 +1667,7 @@ int zfcp_fsf_close_wka_port(struct zfcp_fc_wka_port *wka_port) ...@@ -1667,7 +1667,7 @@ int zfcp_fsf_close_wka_port(struct zfcp_fc_wka_port *wka_port)
zfcp_fsf_req_free(req); zfcp_fsf_req_free(req);
out: out:
spin_unlock_irq(&qdio->req_q_lock); spin_unlock_irq(&qdio->req_q_lock);
if (req && !IS_ERR(req)) if (!retval)
zfcp_dbf_rec_run_wka("fscwp_1", wka_port, req->req_id); zfcp_dbf_rec_run_wka("fscwp_1", wka_port, req->req_id);
return retval; return retval;
} }
......
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