diff --git a/drivers/input/tablet/gtco.c b/drivers/input/tablet/gtco.c
index 7c18249d6c8e820e3fe86ffa66196164dbef2d3f..8b68a210277b242cd8327eaa2d97d13b50c652bc 100644
--- a/drivers/input/tablet/gtco.c
+++ b/drivers/input/tablet/gtco.c
@@ -231,13 +231,17 @@ static void parse_hid_report_descriptor(struct gtco *device, char * report,
 
 	/* Walk  this report and pull out the info we need */
 	while (i < length) {
-		prefix = report[i];
-
-		/* Skip over prefix */
-		i++;
+		prefix = report[i++];
 
 		/* Determine data size and save the data in the proper variable */
-		size = PREF_SIZE(prefix);
+		size = (1U << PREF_SIZE(prefix)) >> 1;
+		if (i + size > length) {
+			dev_err(ddev,
+				"Not enough data (need %d, have %d)\n",
+				i + size, length);
+			break;
+		}
+
 		switch (size) {
 		case 1:
 			data = report[i];
@@ -245,8 +249,7 @@ static void parse_hid_report_descriptor(struct gtco *device, char * report,
 		case 2:
 			data16 = get_unaligned_le16(&report[i]);
 			break;
-		case 3:
-			size = 4;
+		case 4:
 			data32 = get_unaligned_le32(&report[i]);
 			break;
 		}