HID: LG: validate HID output report details

commit 0fb6bd06 upstream

A HID device could send a malicious output report that would cause the
lg, lg3, and lg4 HID drivers to write beyond the output report allocation
during an event, causing a heap overflow:

[  325.245240] usb 1-1: New USB device found, idVendor=046d, idProduct=c287
...
[  414.518960] BUG kmalloc-4096 (Not tainted): Redzone overwritten

Additionally, while lg2 did correctly validate the report details, it was
cleaned up and shortened.

CVE-2013-2893
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

[jmm: backported to 2.6.32]
Signed-off-by: Willy Tarreau <w@1wt.eu>

drivers/hid/hid-lg2ff.c

@@ -65,26 +65,13 @@ int lg2ff_init(struct hid_device *hid)
 	struct hid_report *report;
 	struct hid_input *hidinput = list_entry(hid->inputs.next,
 						struct hid_input, list);
-	struct list_head *report_list =
-			&hid->report_enum[HID_OUTPUT_REPORT].report_list;
 	struct input_dev *dev = hidinput->input;
 	int error;
 
-	if (list_empty(report_list)) {
-		dev_err(&hid->dev, "no output report found\n");
+	/* Check that the report looks ok */
+	report = hid_validate_values(hid, HID_OUTPUT_REPORT, 0, 0, 7);
+	if (!report)
 		return -ENODEV;
-	}
-
-	report = list_entry(report_list->next, struct hid_report, list);
-
-	if (report->maxfield < 1) {
-		dev_err(&hid->dev, "output report is empty\n");
-		return -ENODEV;
-	}
-	if (report->field[0]->report_count < 7) {
-		dev_err(&hid->dev, "not enough values in the field\n");
-		return -ENODEV;
-	}
 
 	lg2ff = kmalloc(sizeof(struct lg2ff_device), GFP_KERNEL);
 	if (!lg2ff)

drivers/hid/hid-lgff.c

@@ -135,27 +135,14 @@ static void hid_lgff_set_autocenter(struct input_dev *dev, u16 magnitude)
 int lgff_init(struct hid_device* hid)
 {
 	struct hid_input *hidinput = list_entry(hid->inputs.next, struct hid_input, list);
-	struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
 	struct input_dev *dev = hidinput->input;
-	struct hid_report *report;
-	struct hid_field *field;
 	const signed short *ff_bits = ff_joystick;
 	int error;
 	int i;
 
-	/* Find the report to use */
-	if (list_empty(report_list)) {
-		err_hid("No output report found");
-		return -1;
-	}
-
 	/* Check that the report looks ok */
-	report = list_entry(report_list->next, struct hid_report, list);
-	field = report->field[0];
-	if (!field) {
-		err_hid("NULL field");
-		return -1;
-	}
+	if (!hid_validate_values(hid, HID_OUTPUT_REPORT, 0, 0, 7))
+		return -ENODEV;
 
 	for (i = 0; i < ARRAY_SIZE(devices); i++) {
 		if (dev->id.vendor == devices[i].idVendor &&