[ 5/5] media: mantis: fix silly crash case

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alan Cox <alan@linux.intel.com>

commit e1d45ae10aea8e8a403e5d96bf5902ee670007ff upstream.

If we set mantis->fe to NULL on an error its not a good idea to then try
passing NULL to the unregister paths and oopsing really.

Resolves-bug: https://bugzilla.kernel.org/show_bug.cgi?id=16473

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Cc: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/media/dvb/mantis/mantis_dvb.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/media/dvb/mantis/mantis_dvb.c
+++ b/drivers/media/dvb/mantis/mantis_dvb.c
@@ -248,8 +248,10 @@ int __devinit mantis_dvb_init(struct man
 err5:
 	tasklet_kill(&mantis->tasklet);
 	dvb_net_release(&mantis->dvbnet);
-	dvb_unregister_frontend(mantis->fe);
-	dvb_frontend_detach(mantis->fe);
+	if (mantis->fe) {
+		dvb_unregister_frontend(mantis->fe);
+		dvb_frontend_detach(mantis->fe);
+	}
 err4:
 	mantis->demux.dmx.remove_frontend(&mantis->demux.dmx, &mantis->fe_mem);