On Thu, Jun 13, 2024 at 5:39 PM Ilya Leoshkevich <iii@xxxxxxxxxxxxx> wrote: > > Even though the KMSAN warnings generated by memchr_inv() are suppressed > by metadata_access_enable(), its return value may still be poisoned. > > The reason is that the last iteration of memchr_inv() returns > `*start != value ? start : NULL`, where *start is poisoned. Because of > this, somewhat counterintuitively, the shadow value computed by > visitSelectInst() is equal to `(uintptr_t)start`. > > The intention behind guarding memchr_inv() behind > metadata_access_enable() is to touch poisoned metadata without > triggering KMSAN, so unpoison its return value. What do you think about applying __no_kmsan_checks to these functions instead?
