From: Ian Abbott <abbotti@mev.co.uk>
Date: Wed, 12 Mar 2008 13:21:58 +0000 (+0000)
Subject: Prevent dereference of NULL chanlist pointer in ai cmdtest leading to
X-Git-Url: http://git.tremily.us/gitweb.cgi?a=commitdiff_plain;h=8e5241e631ce5a742d06d31b95f5b1c3025caaaa;p=comedi.git

Prevent dereference of NULL chanlist pointer in ai cmdtest leading to
kernel Oops.
---

diff --git a/comedi/drivers/ni_labpc.c b/comedi/drivers/ni_labpc.c
index f9afdc8a..d5baf94e 100644
--- a/comedi/drivers/ni_labpc.c
+++ b/comedi/drivers/ni_labpc.c
@@ -783,6 +783,10 @@ static enum scan_mode labpc_ai_scan_mode(const comedi_cmd * cmd)
 	if (cmd->chanlist_len == 1)
 		return MODE_SINGLE_CHAN;
 
+	/* chanlist may be NULL during cmdtest. */
+	if (cmd->chanlist == NULL)
+		return MODE_MULT_CHAN_UP;
+
 	if (CR_CHAN(cmd->chanlist[0]) == CR_CHAN(cmd->chanlist[1]))
 		return MODE_SINGLE_CHAN_INTERVAL;