Add overflow check for descriptor lengths

Author: mvirkkunen

src/descriptor.rs

@@ -60,7 +60,7 @@ impl DescriptorWriter<'_> {
     pub fn write(&mut self, descriptor_type: u8, descriptor: &[u8]) -> Result<()> {
         let length = descriptor.len();
 
-        if self.position + 2 + length > self.buf.len() {
+        if (self.position + 2 + length) > self.buf.len() || (length + 2) > 255 {
             return Err(UsbError::BufferOverflow);
         }
 

src/lib.rs

@@ -45,7 +45,8 @@ pub enum UsbError {
     /// Parsing failed due to invalid input.
     ParseError,
 
-    /// A buffer too short for the data to read was passed.
+    /// A buffer too short for the data to read was passed, or provided data cannot fit within
+    /// length constraints.
     BufferOverflow,
 
     /// Classes attempted to allocate more endpoints than the peripheral supports.