Commit 9d95aa4b authored Aug 02, 2017 by Mike Rapoport Committed by Linus Torvalds Aug 02, 2017

userfaultfd_zeropage: return -ENOSPC in case mm has gone

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: 96333187 ("userfaultfd_copy: return -ENOSPC in case mm has gone")
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 167d0f25

fs/userfaultfd.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -1643,6 +1643,8 @@ 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;

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