ext_config: Fixes config only operations.

Previously we were passing the u64 value of the
pointer to the vector of bytes the extended
report certificates were being loaded from.
However, when handling the case of an extended
configuration only, because the pointer value
of an empty vector is not 0, this was causing
an error in the kernel when attempting to access
the "pointer" being provided. By modifying the
underlying type of `bytes` to `Option<Vec<u8>>`,
it allows the default value to be set to `None`,
and conditionally update the extended config
`certs_address` field when certificate bytes are
present.

Signed-off-by: Larry Dewey <[email protected]>

src/firmware/host/mod.rs

@@ -278,14 +278,17 @@ impl Firmware {
     /// ```
     #[cfg(feature = "snp")]
     pub fn snp_set_ext_config(&mut self, mut new_config: ExtConfig) -> Result<(), UserApiError> {
-        let mut bytes: Vec<u8> = vec![];
+        let mut opt_bytes: Option<Vec<u8>> = None;
 
         if let Some(ref mut certificates) = new_config.certs {
-            bytes = FFI::types::CertTableEntry::uapi_to_vec_bytes(certificates)?;
+            opt_bytes = Some(FFI::types::CertTableEntry::uapi_to_vec_bytes(certificates)?);
         }
 
         let mut new_ext_config: FFI::types::SnpSetExtConfig = new_config.try_into()?;
-        new_ext_config.certs_address = bytes.as_mut_ptr() as u64;
+
+        if let Some(ref mut bytes) = opt_bytes {
+            new_ext_config.certs_address = bytes.as_mut_ptr() as u64;
+        }
 
         SNP_SET_EXT_CONFIG.ioctl(&mut self.0, &mut Command::from_mut(&mut new_ext_config))?;