On 02/26/2018 01:08 PM, Jan Beulich wrote: >>>> On 26.02.18 at 11:00, <aryabinin@xxxxxxxxxxxxx> wrote: >> On 02/26/2018 11:48 AM, tip-bot for Jan Beulich wrote: >>> @@ -351,7 +362,7 @@ static inline bool kasan_page_table(struct seq_file *m, struct pg_state *st, >>> (pgtable_l5_enabled && __pa(pt) == __pa(kasan_zero_p4d)) || >>> __pa(pt) == __pa(kasan_zero_pud)) { >>> pgprotval_t prot = pte_flags(kasan_zero_pte[0]); >>> - note_page(m, st, __pgprot(prot), 5); >>> + note_page(m, st, __pgprot(prot), 0, 5); >> >> Isn't this disables W+X check for kasan page table? >> Methinks it should be 'prot' here. > > Might well be - I actually did ask the question before sending v3, > but didn't get any answer (yet). The kasan_zero_p?d names > suggested to me that this is a shortcut for mappings which > otherwise would be non-present anyway, but that was merely a > guess. kasan_zero_p?? are used to map kasan_zero_page. That's it. > As to W+X checks - I can't see how the result could be > any better if the protections of kasan_zero_pte[0] would be > used: Those can't possibly be applicable independent of VA. I'm not sure I understand what do you mean. If we somehow screw up and accidentally make kasan_zero_pte writable and executable, note_page() should report this. With your patch, it won't work. -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html