fix(pdu): overflow when decoding RsaPublicKey (#409)

crates/ironrdp-pdu/src/rdp/server_license.rs

@@ -217,6 +217,8 @@ pub enum ServerLicenseError {
     InvalidRsaPublicKeyLength,
     #[error("invalid RSA public key data length")]
     InvalidRsaPublicKeyDataLength,
+    #[error("invalid RSA public key bit length")]
+    InvalidRsaPublicKeyBitLength,
     #[error("invalid License Header security flags")]
     InvalidSecurityFlags,
     #[error("the server returned unexpected error: {0:?}")]

crates/ironrdp-pdu/src/rdp/server_license/server_license_request/cert.rs

@@ -160,6 +160,10 @@ impl PduParsing for RsaPublicKey {
             return Err(ServerLicenseError::InvalidRsaPublicKeyLength);
         }
 
+        if bitlen < 8 {
+            return Err(ServerLicenseError::InvalidRsaPublicKeyBitLength);
+        }
+
         let datalen = stream.read_u32::<LittleEndian>()?;
         if datalen != (bitlen / 8) - 1 {
             return Err(ServerLicenseError::InvalidRsaPublicKeyDataLength);