It was checking the first character of the message for a null byte, but not whether the message string pointer itself was null. Change-Id: Iddef1e22c35b55c8c898670576ab416dd1023d7c Reviewed-on: https://gem5-review.googlesource.com/12252 Reviewed-by: Gabe Black <gabeblack@google.com> Maintainer: Gabe Black <gabeblack@google.com>