From: Ian Abbott <abbotti@mev.co.uk>
Date: Thu, 15 Dec 2011 19:52:32 +0000 (+0000)
Subject: dt282x: don't access *data when insn->n == 0
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=7ca6209a564ff97db18a1672eb08e408de426726;p=comedi.git

dt282x: don't access *data when insn->n == 0

Due to recent change to do_insnlist_ioctl() and do_insn_ioctl(), the
'data' pointer will be NULL when insn->n == 0.  Do not access *data
in this case.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
---

diff --git a/comedi/drivers/dt282x.c b/comedi/drivers/dt282x.c
index 74f1f40f..dc703f7f 100644
--- a/comedi/drivers/dt282x.c
+++ b/comedi/drivers/dt282x.c
@@ -940,6 +940,9 @@ static int dt282x_ns_to_timer(int *nanosec, int round_mode)
 static int dt282x_ao_insn_read(comedi_device * dev, comedi_subdevice * s,
 	comedi_insn * insn, lsampl_t * data)
 {
+	if (insn->n == 0)
+		return 0;
+
 	data[0] = devpriv->ao[CR_CHAN(insn->chanspec)];
 
 	return 1;
@@ -951,6 +954,9 @@ static int dt282x_ao_insn_write(comedi_device * dev, comedi_subdevice * s,
 	sampl_t d;
 	unsigned int chan;
 
+	if (insn->n == 0)
+		return 0;
+
 	chan = CR_CHAN(insn->chanspec);
 	d = data[0];
 	d &= (1 << boardtype.dabits) - 1;