From: Ian Abbott <abbotti@mev.co.uk>
Date: Thu, 15 Dec 2011 18:37:34 +0000 (+0000)
Subject: poc: don't access *data when insn->n == 0
X-Git-Url: http://git.tremily.us/gitweb.cgi?a=commitdiff_plain;h=ffd3dc2117a28ac9508df1d71f6892cbc3342d04;p=comedi.git

poc: 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/poc.c b/comedi/drivers/poc.c
index 4aa14762..3a22732e 100644
--- a/comedi/drivers/poc.c
+++ b/comedi/drivers/poc.c
@@ -175,6 +175,9 @@ static int readback_insn(comedi_device * dev, comedi_subdevice * s,
 {
 	int chan;
 
+	if (insn->n == 0)
+		return 0;
+
 	chan = CR_CHAN(insn->chanspec);
 	data[0] = ((lsampl_t *) dev->private)[chan];
 
@@ -192,6 +195,9 @@ static int dac02_ao_winsn(comedi_device * dev, comedi_subdevice * s,
 	int chan;
 	int output;
 
+	if (insn->n == 0)
+		return 0;
+
 	chan = CR_CHAN(insn->chanspec);
 	((lsampl_t *) dev->private)[chan] = data[0];
 	output = data[0];