dyndbg: fix use before null check
In commit
a2d375eda771 ("dyndbg: refine export, rename to
dynamic_debug_exec_queries()"), a string is copied before checking it
isn't NULL. Fix this, report a usage/interface error, and return the
proper error code.
Fixes: a2d375eda771 ("dyndbg: refine export, rename to dynamic_debug_exec_queries()")
Cc: stable@vger.kernel.org
--
-v2 drop comment tweak, improve commit message
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20201209183625.2432329-1-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>