Re: [RFC][PATCH 1/3] exec: Move unshare_files down to avoid locks being dropped on exec.

[Oleg Nesterov]

On 09/16, Eric W. Biederman wrote:
>
> @@ -1291,6 +1292,12 @@ int flush_old_exec(struct linux_binprm * bprm)
>       flush_thread();
>       current->personality &= ~bprm->per_clear;
>
> +     retval = unshare_files(&displaced);

I was going to sugget basically the same changes, please feel free to add
my reviewed-by to 1-3.


Just for record. If we should really worry about unshare_files() failure
after de_thread() (imo we shouldn't), we can do another change:

        __do_execve_file:

                unshare_fd(CLONE_FILES, &bprm->unshared_copy);
                ...


        flush_old_exec:

                de_thread();

                if (bprm->unshared_copy) {
                        // now that we killed sub-threads recheck
                        if (current->files->count > 1) {
                                put_files_struct(current->files);
                                current->files = bprm->unshared_copy;
                        } else {
                                put_files_struct(bprm->unshared_copy);
                        }
                                
                }

but again, I think your series is fine.

Oleg.