From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BE805C433EF for ; Tue, 1 Feb 2022 20:58:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242672AbiBAU6U (ORCPT ); Tue, 1 Feb 2022 15:58:20 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:55472 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242531AbiBAU6S (ORCPT ); Tue, 1 Feb 2022 15:58:18 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 7A892B82F8D for ; Tue, 1 Feb 2022 20:58:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DCF7CC340EB; Tue, 1 Feb 2022 20:58:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1643749096; bh=fqo/Cs9VmeENzUszBePsTs/X5/ArzOQQR2v+mm2TnSc=; h=Date:To:From:Subject:From; b=F5Jsn1YWOiYkfqTmbFsr8zTQJN5wnY6BjNwP99Wditv/qmkiJbxSnoCEm6+7haOer rO+Yp1xNHrnkzXk5E5D6LWA/rFqR2Lmx9eJ5bJcEeZ676hgZ2eID4mEK5aKoyipyXy W7TiXROZEQANuMe5Ch086SZSO/t+Qhvv/n2W7qno= Received: by hp1 (sSMTP sendmail emulation); Tue, 01 Feb 2022 12:58:14 -0800 Date: Tue, 01 Feb 2022 12:58:14 -0800 To: mm-commits@vger.kernel.org, kirill.shutemov@linux.intel.com, jhubbard@nvidia.com, jgg@ziepe.ca, jgg@nvidia.com, jack@suse.cz, david@redhat.com, alex.williamson@redhat.com, aarcange@redhat.com, peterx@redhat.com, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-fix-invalid-page-pointer-returned-with-foll_pin-gups.patch added to -mm tree Message-Id: <20220201205814.DCF7CC340EB@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm: fix invalid page pointer returned with FOLL_PIN gups has been added to the -mm tree. Its filename is mm-fix-invalid-page-pointer-returned-with-foll_pin-gups.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/mm-fix-invalid-page-pointer-returned-with-foll_pin-gups.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/mm-fix-invalid-page-pointer-returned-with-foll_pin-gups.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Peter Xu Subject: mm: fix invalid page pointer returned with FOLL_PIN gups Patch series "mm/gup: some cleanups", v2. This patch (of 4): Alex reported invalid page pointer returned with pin_user_pages_remote() from vfio after upstream commit 4b6c33b32296 ("vfio/type1: Prepare for batched pinning with struct vfio_batch"). This problem breaks NVIDIA vfio mdev. It turns out that it's not the fault of the vfio commit; however after vfio switches to a full page buffer to store the page pointers it starts to expose the problem easier. The problem is for VM_PFNMAP vmas we should normally fail with an -EFAULT then vfio will carry on to handle the MMIO regions. However when the bug triggered, follow_page_mask() returned -EEXIST for such a page, which will jump over the current page, leaving that entry in **pages untouched. However the caller is not aware of it, hence the caller will reference the page as usual even if the pointer data can be anything. We had that -EEXIST logic since commit 1027e4436b6a ("mm: make GUP handle pfn mapping unless FOLL_GET is requested") which seems very reasonable. It could be that when we reworked GUP with FOLL_PIN we could have overlooked that special path in commit 3faa52c03f44 ("mm/gup: track FOLL_PIN pages"), even if that commit rightfully touched up follow_devmap_pud() on checking FOLL_PIN when it needs to return an -EEXIST. Attaching the Fixes to the FOLL_PIN rework commit, as it happened later than 1027e4436b6a. Link: https://lkml.kernel.org/r/20220201101108.306062-1-jhubbard@nvidia.com Link: https://lkml.kernel.org/r/20220201101108.306062-2-jhubbard@nvidia.com Fixes: 3faa52c03f44 ("mm/gup: track FOLL_PIN pages") Signed-off-by: Peter Xu Signed-off-by: John Hubbard Reviewed-by: John Hubbard Reported-by: Alex Williamson Debugged-by: Alex Williamson Tested-by: Alex Williamson Cc: Andrea Arcangeli Cc: Jan Kara Cc: Kirill A. Shutemov Cc: David Hildenbrand Cc: Jason Gunthorpe Cc: Jason Gunthorpe Signed-off-by: Andrew Morton --- mm/gup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/gup.c~mm-fix-invalid-page-pointer-returned-with-foll_pin-gups +++ a/mm/gup.c @@ -440,7 +440,7 @@ static int follow_pfn_pte(struct vm_area pte_t *pte, unsigned int flags) { /* No page to get reference */ - if (flags & FOLL_GET) + if (flags & (FOLL_GET | FOLL_PIN)) return -EFAULT; if (flags & FOLL_TOUCH) { _ Patches currently in -mm which might be from peterx@redhat.com are mm-fix-invalid-page-pointer-returned-with-foll_pin-gups.patch