Hi, On Sun, Jun 07, 2020 at 09:26:26PM +0200, Arnd Bergmann wrote:
> I think you have to use get_user_pages() though instead of > get_user_pages_fast(), > in order to be able to check the permission bits to prevent doing a > copy_to_user() > into read-only mappings. i was not aware of this, is it documented somewhere ?, afaiu, difference b/n get_user_pages_fast() & get_user_pages() is that fast version will try to pin pages w/o acquiring mmap_sem if possible. > Do you want me to review the uaccess patch to look for any missing > corner cases, or do you want to do the whole set of user access helpers > first? i will cleanup and probably post RFC initially for the changes handling copy_{from,to}_user() to get feedback. Regards afzal