Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753453AbdHIRRd (ORCPT ); Wed, 9 Aug 2017 13:17:33 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:38658 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753107AbdHIQxw (ORCPT ); Wed, 9 Aug 2017 12:53:52 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mike Rapoport , Andrea Arcangeli , "Dr. David Alan Gilbert" , Pavel Emelyanov , Michal Hocko , Andrew Morton , Linus Torvalds Subject: [PATCH 4.12 020/106] userfaultfd_zeropage: return -ENOSPC in case mm has gone Date: Wed, 9 Aug 2017 09:52:04 -0700 Message-Id: <20170809164518.784275253@linuxfoundation.org> X-Mailer: git-send-email 2.14.0 In-Reply-To: <20170809164515.714288642@linuxfoundation.org> References: <20170809164515.714288642@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1542 Lines: 43 4.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mike Rapoport 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 --- fs/userfaultfd.c | 2 ++ 1 file changed, 2 insertions(+) --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1645,6 +1645,8 @@ static int userfaultfd_zeropage(struct u 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;