Re: [PATCH] userfaultfd_release: always remove uffd flags and clear vm_userfaultfd_ctx

2019-08-20 Thread Kefeng Wang
On 2019/8/21 0:02, Oleg Nesterov wrote: > userfaultfd_release() should clear vm_flags/vm_userfaultfd_ctx even > if mm->core_state != NULL. > > Otherwise a page fault can see userfaultfd_missing() == T and use an > already freed userfaultfd_ctx. > > Reported-by: Kefeng Wang > Fixes: 04f5866e41fb

Re: [PATCH] userfaultfd_release: always remove uffd flags and clear vm_userfaultfd_ctx

2019-08-20 Thread Andrea Arcangeli
On Tue, Aug 20, 2019 at 06:02:38PM +0200, Oleg Nesterov wrote: > userfaultfd_release() should clear vm_flags/vm_userfaultfd_ctx even > if mm->core_state != NULL. > > Otherwise a page fault can see userfaultfd_missing() == T and use an > already freed userfaultfd_ctx. > > Reported-by: Kefeng Wang

[PATCH] userfaultfd_release: always remove uffd flags and clear vm_userfaultfd_ctx

2019-08-20 Thread Oleg Nesterov
userfaultfd_release() should clear vm_flags/vm_userfaultfd_ctx even if mm->core_state != NULL. Otherwise a page fault can see userfaultfd_missing() == T and use an already freed userfaultfd_ctx. Reported-by: Kefeng Wang Fixes: 04f5866e41fb ("coredump: fix race condition between