I'd really like to have errors on overflow, at least as an option, even if it is costly in terms of performance. Is there a Trac ticket or something for this?
as far as safety aspects are concerned, you might consider adding yourself to http://hackage.haskell.org/trac/ghc/ticket/1380 ? although i understand that you also want checking for overflow in otherwise unrestricted programs, which would be a separate issue/ticket.
Haskell's FFI makes it as vulnerable as the libraries it interfaces to.
if you have anything beyond unsafe foreign libs, or invalid indexing in mind, could you add it to that ticket, please? and perhaps to http://haskell.org/haskellwiki/Safely_running_untrusted_Haskell_code which concerns lessons learned about guarding lambdabot against exploits? lambdabot has been boldly going where no one has gone before for quite a while now, but that doesn't ensure that all holes have been plugged. claus