Messages in this thread | | | Date | Mon, 8 Jun 2020 16:48:34 +0530 | From | afzal mohammed <> | Subject | Re: ARM: vmsplit 4g/4g |
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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
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