userfaultfd_release: always remove uffd flags and clear vm_userfaultfd_ctx

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.

Link: http://lkml.kernel.org/r/[email protected]
Fixes: 04f5866e41fb ("coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping")
Signed-off-by: Oleg Nesterov <[email protected]>
Reported-by: Kefeng Wang <[email protected]>
Reviewed-by: Andrea Arcangeli <[email protected]>
Tested-by: Kefeng Wang <[email protected]>
Cc: Peter Xu <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Jann Horn <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions