On Wed, May 2, 2018 at 7:25 PM, Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote: > On Wed, May 2, 2018 at 5:36 PM, Kirill A. Shutemov > <kirill.shutemov@xxxxxxxxxxxxxxx> wrote: >> On Wed, May 02, 2018 at 02:38:42PM +0000, Andrey Konovalov wrote: >>> > Does having a tagged address here makes any difference? I couldn't hit a >>> > failure with my simple tests (LD_PRELOAD a library that randomly adds >>> > tags to pointers returned by malloc). >>> >>> I think you're right, follow_page_mask is only called from >>> __get_user_pages, which already untagged the address. I'll remove >>> untagging here. >> >> It also called from follow_page(). Have you covered all its callers? > > Oh, missed that, will take a look. I wasn't able to find anything that calls follow_page with pointers passed from userspace except for the memory subsystem syscalls, and we deliberately don't add untagging in those.
