From: Arun Sharma <arun.sharma@intel.com>

A script such as

  #!/bin/foo.bar
  ...

where /bin/foo.bar is handled by binfmt_misc, is not handled correctly i.e.
the interpreter of foo.bar doesn't receive the correct arguments.

The binfmt_misc handler requires that bprm->filename is appropriately
filled so that the argv[1] could be correctly passed to the interpreter.

However, binfmt_script, as it exists today doesn't populate bprm->filename
correctly.

Another motivation for this patch is the output of ps.  Emulators which use
binfmt_misc may want to keep the output of ps consistent with native
execution.  This requires preserving bprm->filename.  The attached patch
guarantees this even if we have to go through several binfmt handlers
(think of finite loops involving binfmt_script and binfmt_misc).