From: Ian Abbott <abbotti@mev.co.uk>
Date: Thu, 15 Dec 2011 21:04:50 +0000 (+0000)
Subject: ni_at_ao: don't access *data when insn->n == 0
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=e576f852e8f1f35355b7586d8203386506ebe31a;p=comedi.git

ni_at_ao: 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/ni_at_ao.c b/comedi/drivers/ni_at_ao.c
index 17d055e6..d0dcf45e 100644
--- a/comedi/drivers/ni_at_ao.c
+++ b/comedi/drivers/ni_at_ao.c
@@ -434,6 +434,9 @@ static int atao_calib_insn_write(comedi_device * dev, comedi_subdevice * s,
 	unsigned int bitstring, bit;
 	unsigned int chan = CR_CHAN(insn->chanspec);
 
+	if (insn->n == 0)
+		return 0;
+
 	bitstring = ((chan & 0x7) << 8) | (data[insn->n - 1] & 0xff);
 
 	for (bit = 1 << (11 - 1); bit; bit >>= 1) {