staging: comedi: drivers: properly validate cmd->scan_end_arg

When the async command 'scan_end_src' is TRIG_COUNT the 'scan_end_arg'
is the cmd->chanlist_len. Fix a couple open-coded drivers. Add the
check to the drivers that do not validate this command argument.

The core validates that the cmd->chanlist_len is <= s->len_chanlist.
During the post config after the attach the core also make sure that
the s->len_chanlist is initialized. For clarity, initialize the
s->len_chanlist in a couple drivers that are relying on the core to
initialize it to '1'.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/staging/comedi/drivers/comedi_parport.c b/drivers/staging/comedi/drivers/comedi_parport.c
index 9de81c7712fb..50723b940630 100644
--- a/drivers/staging/comedi/drivers/comedi_parport.c
+++ b/drivers/staging/comedi/drivers/comedi_parport.c
@@ -181,7 +181,7 @@ static int parport_intr_cmdtest(struct comedi_device *dev,
 	err |= cfc_check_trigger_arg_is(&cmd->start_arg, 0);
 	err |= cfc_check_trigger_arg_is(&cmd->scan_begin_arg, 0);
 	err |= cfc_check_trigger_arg_is(&cmd->convert_arg, 0);
-	err |= cfc_check_trigger_arg_is(&cmd->scan_end_arg, 1);
+	err |= cfc_check_trigger_arg_is(&cmd->scan_end_arg, cmd->chanlist_len);
 	err |= cfc_check_trigger_arg_is(&cmd->stop_arg, 0);
 
 	if (err)
@@ -295,6 +295,7 @@ static int parport_attach(struct comedi_device *dev,
 		s->maxdata	= 1;
 		s->range_table	= &range_digital;
 		s->insn_bits	= parport_intr_insn_bits;
+		s->len_chanlist	= 1;
 		s->do_cmdtest	= parport_intr_cmdtest;
 		s->do_cmd	= parport_intr_cmd;
 		s->cancel	= parport_intr_cancel;