From: Mike Rapoport Date: Wed, 2 Aug 2017 20:32:15 +0000 (-0700) Subject: userfaultfd_zeropage: return -ENOSPC in case mm has gone X-Git-Tag: v4.12.6~88 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=57f793272176f251e73f90a7f421972349fe9631;p=thirdparty%2Fkernel%2Fstable.git userfaultfd_zeropage: return -ENOSPC in case mm has gone commit 9d95aa4bada24be35bb94827a55e1d6e243d866e upstream. In the non-cooperative userfaultfd case, the process exit may race with outstanding mcopy_atomic called by the uffd monitor. Returning -ENOSPC instead of -EINVAL when mm is already gone will allow uffd monitor to distinguish this case from other error conditions. Unfortunately I overlooked userfaultfd_zeropage when updating userfaultd_copy(). Link: http://lkml.kernel.org/r/1501136819-21857-1-git-send-email-rppt@linux.vnet.ibm.com Fixes: 96333187ab162 ("userfaultfd_copy: return -ENOSPC in case mm has gone") Signed-off-by: Mike Rapoport Cc: Andrea Arcangeli Cc: "Dr. David Alan Gilbert" Cc: Pavel Emelyanov Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 1d622f276e3a2..c0b2787bdcd43 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1645,6 +1645,8 @@ static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx, ret = mfill_zeropage(ctx->mm, uffdio_zeropage.range.start, uffdio_zeropage.range.len); mmput(ctx->mm); + } else { + return -ENOSPC; } if (unlikely(put_user(ret, &user_uffdio_zeropage->zeropage))) return -EFAULT;