fix: DisconnectReason::decode should return error on zero length list (…

…paradigmxyz#7284)

crates/net/eth-wire/src/disconnect.rs

@@ -129,9 +129,14 @@ impl Decodable for DisconnectReason {
             // this should be a list, so decode the list header. this should advance the buffer so
             // buf[0] is the first (and only) element of the list.
             let header = Header::decode(buf)?;
+
             if !header.list {
                 return Err(RlpError::UnexpectedString)
             }
+
+            if header.payload_length != 1 {
+                return Err(RlpError::ListLengthMismatch { expected: 1, got: header.payload_length })
+            }
         }
 
         // geth rlp encodes [`DisconnectReason::DisconnectRequested`] as 0x00 and not as empty
@@ -232,6 +237,14 @@ mod tests {
         assert!(DisconnectReason::decode(&mut &[0u8; 3][..]).is_err())
     }
 
+    #[test]
+    fn test_reason_zero_length_list() {
+        let list_with_zero_length = hex::decode("c000").unwrap();
+        let res = DisconnectReason::decode(&mut &list_with_zero_length[..]);
+        assert!(res.is_err());
+        assert_eq!(res.unwrap_err().to_string(), "unexpected list length (got 0, expected 1)")
+    }
+
     #[test]
     fn disconnect_encoding_length() {
         let all_reasons = all_reasons();