On Wed, Mar 01, 2017 at 07:48:00PM +0100, Dmitry Vyukov wrote: > Hello, > > I've got the following use-after-free report while running syzkaller > fuzzer on 86292b33d4b79ee03e2f43ea0381ef85f077c760: Yes, I posted the fix for this one last Friday, I found it during stress testing, it triggered the first time post-upstream merging despite I was running the same stress testing with SLUB poisoning enabled before. This affects all apps, also the ones that don't use userfaultfd, it's a locking issue. Furthermore the cost of userfaultfd_exit was not acceptable, if something it had to be activated by a flag in mm->flags (such an optimization would have been absolutely trivial though). Thankfully I realized another feature (UFFDIO_COPY -ENOSPC retval) can provide the same information at zero cost so I could drop userfaultfd_exit as a whole. https://marc.info/?l=linux-mm&m=148796041217814&w=2 The fix is already included in -mm along with the other fix for VM_FAULT_NOPAGE. Thanks, Andrea
