From patchwork Fri May 13 14:24:03 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 572514 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 4598CC4332F for ; Fri, 13 May 2022 14:31:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1380864AbiEMObg (ORCPT ); Fri, 13 May 2022 10:31:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1381193AbiEMObJ (ORCPT ); Fri, 13 May 2022 10:31:09 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C32B4197F67; Fri, 13 May 2022 07:28:36 -0700 (PDT) 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 dfw.source.kernel.org (Postfix) with ESMTPS id 3080C62175; Fri, 13 May 2022 14:28:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 12234C34100; Fri, 13 May 2022 14:28:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1652452115; bh=jrRvUIKYf1n5UNwFP4Jhq6pBwQ4NWVjBYb4qxpwM3tw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LHl2ywcbzOHeLrZNPgQT9tEt0by+/mHq8C+5VpSxE/OJMizFQ0vAOjlxohlIRABM+ nBRe7HQe4+k6E1ZSs8LHPwyCdGNMf6+T3mS3YE+sZUbCcmls3CzrDa1eaZifYRPP8q Ku+UiN9DlQbgotsAAw4WZfE/zX4CWUIVBscCYZqY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Peter Xu , John Hubbard , Claudio Imbrenda , Alex Williamson , Christoph Hellwig , Jan Kara , Andrea Arcangeli , "Kirill A. Shutemov" , Jason Gunthorpe , David Hildenbrand , Lukas Bulwahn , "Matthew Wilcox (Oracle)" , Jason Gunthorpe , Andrew Morton , Linus Torvalds Subject: [PATCH 5.15 21/21] mm: fix invalid page pointer returned with FOLL_PIN gups Date: Fri, 13 May 2022 16:24:03 +0200 Message-Id: <20220513142230.486646732@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220513142229.874949670@linuxfoundation.org> References: <20220513142229.874949670@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Peter Xu commit 7196040e19ad634293acd3eff7083149d7669031 upstream. Patch series "mm/gup: some cleanups", v5. This patch (of 5): 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"). 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. [jhubbard@nvidia.com: added some tags, removed a reference to an out of tree module.] Link: https://lkml.kernel.org/r/20220207062213.235127-1-jhubbard@nvidia.com Link: https://lkml.kernel.org/r/20220204020010.68930-1-jhubbard@nvidia.com Link: https://lkml.kernel.org/r/20220204020010.68930-2-jhubbard@nvidia.com Fixes: 3faa52c03f44 ("mm/gup: track FOLL_PIN pages") Signed-off-by: Peter Xu Signed-off-by: John Hubbard Reviewed-by: Claudio Imbrenda Reported-by: Alex Williamson Debugged-by: Alex Williamson Tested-by: Alex Williamson Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Cc: Andrea Arcangeli Cc: Kirill A. Shutemov Cc: Jason Gunthorpe Cc: David Hildenbrand Cc: Lukas Bulwahn Cc: Matthew Wilcox (Oracle) Cc: Jason Gunthorpe Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/gup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/gup.c +++ b/mm/gup.c @@ -465,7 +465,7 @@ 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) {