[PATCH 3/5] exec: Remove recursion from search_binary_handler

[Linus Torvalds]

On Sat, May 9, 2020 at 9:30 PM Tetsuo Handa
<penguin-kernel at i-love.sakura.ne.jp> wrote:
>
> Wouldn't this change cause
>
>         if (fd_binary > 0)
>                 ksys_close(fd_binary);
>         bprm->interp_flags = 0;
>         bprm->interp_data = 0;
>
> not to be called when "Search for the interpreter" failed?

Good catch. We seem to have some subtle magic wrt the fd_binary file
descriptor, which depends on the recursive behavior.

I'm not seeing how to fix it cleanly with the "turn it into a loop".
Basically, that binfmt_misc use-case isn't really a tail-call.

Eric, ideas?

                 Linus