irda: test index before read in stir421x_patch_device()

Test whether index exceeds fw->size before reading the element
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/net/irda/irda-usb.c

@@ -1122,11 +1122,12 @@ static int stir421x_patch_device(struct irda_usb_cb *self)
                  * The actual image starts after the "STMP" keyword
                  * so forward to the firmware header tag
                  */
-                for (i = 0; (fw->data[i] != STIR421X_PATCH_END_OF_HDR_TAG)
-			     && (i < fw->size); i++) ;
+                for (i = 0; i < fw->size && fw->data[i] !=
+				STIR421X_PATCH_END_OF_HDR_TAG; i++)
+			;
                 /* here we check for the out of buffer case */
-                if ((STIR421X_PATCH_END_OF_HDR_TAG == fw->data[i])
-                    && (i < STIR421X_PATCH_CODE_OFFSET)) {
+                if (i < STIR421X_PATCH_CODE_OFFSET && i < fw->size &&
+				STIR421X_PATCH_END_OF_HDR_TAG == fw->data[i]) {
                         if (!memcmp(fw->data + i + 1, STIR421X_PATCH_STMP_TAG,
                                     sizeof(STIR421X_PATCH_STMP_TAG) - 1)) {