From 875b4e3763dbc941f15143dd1a18d10bb0be303b Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@chromium.org>
Date: Wed, 28 Aug 2013 22:31:28 +0200
Subject: HID: ntrig: validate feature report details

A HID device could send a malicious feature report that would cause the
ntrig HID driver to trigger a NULL dereference during initialization:

[57383.031190] usb 3-1: New USB device found, idVendor=1b96, idProduct=0001
...
[57383.315193] BUG: unable to handle kernel NULL pointer dereference at 0000000000000030
[57383.315308] IP: [<ffffffffa08102de>] ntrig_probe+0x25e/0x420 [hid_ntrig]

CVE-2013-2896

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@kernel.org
Signed-off-by: Rafi Rubin <rafi@seas.upenn.edu>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/hid-ntrig.c b/drivers/hid/hid-ntrig.c
index 98d1fdf..600f207 100644
--- a/drivers/hid/hid-ntrig.c
+++ b/drivers/hid/hid-ntrig.c
@@ -115,7 +115,8 @@ static inline int ntrig_get_mode(struct hid_device *hdev)
 	struct hid_report *report = hdev->report_enum[HID_FEATURE_REPORT].
 				    report_id_hash[0x0d];
 
-	if (!report)
+	if (!report || report->maxfield < 1 ||
+	    report->field[0]->report_count < 1)
 		return -EINVAL;
 
 	hid_hw_request(hdev, report, HID_REQ_GET_REPORT);
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