On Sat, May 26, 2018 at 5:32 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> I went through some old threads from 2012 when e268337dfe26 was
> introduced, and later when things got looked at during DirtyCOW. There
> was discussion about removing FOLL_FORCE (in order to block writes on
> a read-only memory region).
Side note, we did that for /dev/mem, and things broke.
Thus commit f511c0b17b08 "Yes, people use FOLL_FORCE ;)"
Side note, that very sam ecommit f511c0b17b08 is also the explanation for
why the patch under discussion now seems broken.
People really do use "write to /proc/self/mem" as a way to keep the
mappings read-only, but have a way to change them when required.
Linus
