On Mon, Jun 14, 2021 at 9:45 AM Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>
> /* A task may only write when it was the opener. */
> - if (file->private_data != current->mm)
> + if (!file->private_data || file->private_data != current->mm)
I don't think this is necessary.
If file->private_data is NULL, then the old test for private_data !=
current->mm will still work just fine.
Because if you can fool kernel threads to do the write for you, you
have bigger security issues than that test.
Linus
