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linux/drivers/s390
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Steffen Maier 2dfa6688aa scsi: zfcp: fix use-after-free by not tracing WKA port open/close on failed send 
Dan Carpenter kindly reported:
<quote>
The patch d27a7cb919: "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: Dan Carpenter <dan.carpenter@oracle.com>
Suggested-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
Fixes: d27a7cb919 ("zfcp: trace on request for open and close of WKA port")
Cc: <stable@vger.kernel.org> #2.6.38+
Reviewed-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Reviewed-by: Jens Remus <jremus@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2017-02-09 19:28:19 -05:00
..
block s390/dasd: channel path aware error recovery 2016-12-12 12:05:03 +01:00
char Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2016-12-13 16:33:33 -08:00
cio s390: cio: make it explicitly non-modular 2016-10-31 17:55:32 +01:00
crypto s390/zcrypt: Convert to PM ops 2016-12-02 07:36:22 +01:00
net s390/net: use net core MTU range checking 2016-10-20 14:51:10 -04:00
scsi scsi: zfcp: fix use-after-free by not tracing WKA port open/close on failed send 2017-02-09 19:28:19 -05:00
virtio s390: virtio: make ccw explicitly non-modular 2016-10-31 17:55:46 +01:00
Makefile virtio/s390: rename drivers/s390/kvm -> drivers/s390/virtio 2015-07-07 14:27:06 +03:00