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/20190820160237.GB4983@redhat.com Fixes: 04f5866e ("coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping") Signed-off-by:Oleg Nesterov <oleg@redhat.com> Reported-by:
Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by:
Andrea Arcangeli <aarcange@redhat.com> Tested-by:
Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Peter Xu <peterx@redhat.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: <stable@vger.kernel.org> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
parent
7b2b55da
Please register or sign in to comment