HID: LG: validate HID output report details

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>

1 files changed, 6 insertions, 23 deletions

diff --git a/drivers/hid/hid-lg3ff.c b/drivers/hid/hid-lg3ff.c
index e52f181..8c2da18 100644
--- a/drivers/hid/hid-lg3ff.c
+++ b/drivers/hid/hid-lg3ff.c
@@ -66,10 +66,11 @@ static int hid_lg3ff_play(struct input_dev *dev, void *data,
 	int x, y;
 
 /*
- * Maxusage should always be 63 (maximum fields)
- * likely a better way to ensure this data is clean
+ * Available values in the field should always be 63, but we only use up to
+ * 35. Instead, clear the entire area, however big it is.
  */
-	memset(report->field[0]->value, 0, sizeof(__s32)*report->field[0]->maxusage);
+	memset(report->field[0]->value, 0,
+	       sizeof(__s32) * report->field[0]->report_count);
 
 	switch (effect->type) {
 	case FF_CONSTANT:
@@ -129,32 +130,14 @@ static const signed short ff3_joystick_ac[] = {
 int lg3ff_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 = ff3_joystick_ac;
 	int error;
 	int i;
 
-	/* Find the report to use */
-	if (list_empty(report_list)) {
-		hid_err(hid, "No output report found\n");
-		return -1;
-	}
-
 	/* Check that the report looks ok */
-	report = list_entry(report_list->next, struct hid_report, list);
-	if (!report) {
-		hid_err(hid, "NULL output report\n");
-		return -1;
-	}
-
-	field = report->field[0];
-	if (!field) {
-		hid_err(hid, "NULL field\n");
-		return -1;
-	}
+	if (!hid_validate_values(hid, HID_OUTPUT_REPORT, 0, 0, 35))
+		return -ENODEV;
 
 	/* Assume single fixed device G940 */
 	for (i = 0; ff_bits[i] >= 0; i++)