[Trusty][Utopic][CVE-2014-3186] HID: picolcd: sanity check report size in raw_event() callback

[Luis Henriques]

From: Jiri Kosina <jkosina at suse.cz>

The report passed to us from transport driver could potentially be
arbitrarily large, therefore we better sanity-check it so that raw_data
that we hold in picolcd_pending structure are always kept within proper
bounds.

Cc: stable at vger.kernel.org
Reported-by: Steven Vittitoe <scvitti at google.com>
Signed-off-by: Jiri Kosina <jkosina at suse.cz>
(cherry picked from commit 844817e47eef14141cf59b8d5ac08dd11c0a9189)
CVE-2014-3186
BugLink: http://bugs.launchpad.net/bugs/1370038
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/hid/hid-picolcd_core.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/hid/hid-picolcd_core.c b/drivers/hid/hid-picolcd_core.c
index acbb021065ec..020df3c2e8b4 100644
--- a/drivers/hid/hid-picolcd_core.c
+++ b/drivers/hid/hid-picolcd_core.c
@@ -350,6 +350,12 @@ static int picolcd_raw_event(struct hid_device *hdev,
 	if (!data)
 		return 1;
 
+	if (size > 64) {
+		hid_warn(hdev, "invalid size value (%d) for picolcd raw event\n",
+				size);
+		return 0;
+	}
+
 	if (report->id == REPORT_KEY_STATE) {
 		if (data->input_keys)
 			ret = picolcd_raw_keypad(data, report, raw_data+1, size-1);
-- 
2.1.0