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 X-Spam-Level: X-Spam-Status: No, score=-9.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2B396C3A5A2 for ; Fri, 23 Aug 2019 22:18:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0354120850 for ; Fri, 23 Aug 2019 22:18:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="Py/+nEgU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2436999AbfHWWSS (ORCPT ); Fri, 23 Aug 2019 18:18:18 -0400 Received: from hqemgate14.nvidia.com ([216.228.121.143]:10172 "EHLO hqemgate14.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405055AbfHWWSM (ORCPT ); Fri, 23 Aug 2019 18:18:12 -0400 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqemgate14.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Fri, 23 Aug 2019 15:18:11 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Fri, 23 Aug 2019 15:18:11 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Fri, 23 Aug 2019 15:18:11 -0700 Received: from HQMAIL110.nvidia.com (172.18.146.15) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Fri, 23 Aug 2019 22:18:11 +0000 Received: from HQMAIL101.nvidia.com (172.20.187.10) by hqmail110.nvidia.com (172.18.146.15) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Fri, 23 Aug 2019 22:18:09 +0000 Received: from hqnvemgw01.nvidia.com (172.20.150.20) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Fri, 23 Aug 2019 22:18:09 +0000 Received: from rcampbell-dev.nvidia.com (Not Verified[10.110.48.66]) by hqnvemgw01.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Fri, 23 Aug 2019 15:18:09 -0700 From: Ralph Campbell To: CC: , , , , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Jason Gunthorpe , Andrew Morton , "Christoph Hellwig" , Ralph Campbell Subject: [PATCH 2/2] mm/hmm: hmm_range_fault() infinite loop Date: Fri, 23 Aug 2019 15:17:53 -0700 Message-ID: <20190823221753.2514-3-rcampbell@nvidia.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190823221753.2514-1-rcampbell@nvidia.com> References: <20190823221753.2514-1-rcampbell@nvidia.com> MIME-Version: 1.0 X-NVConfidentiality: public Content-Transfer-Encoding: quoted-printable Content-Type: text/plain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1566598691; bh=H0xCNFTKe9KT+REMj7c8+VZLGl6bVqw61h/FiyncJWs=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:X-NVConfidentiality: Content-Transfer-Encoding:Content-Type; b=Py/+nEgUIjhIZbSu7cNxlYuXfEoZik6c6x3VzsIs38x5i57ELvn5JRlErcGl1DLSm OPm61FMKufS0D/REIhl99DbtgwiyufGaCiuLtD8EtwBjFC2UWBQZpe9L/R3XF+LaCc pQYGZc/IOqyS2G+1GlYqg8wySXYGft4IwgvkW/lneMjxIKzhvyBTvhGlLWRH96F7be Fjkol1850wsIJiuiZ2VkFIBG8mjuuMqEH9je3XnpBUdEIlN96xf1lgzs2F34kKu7gW AU8/C52wqkZa4aBqUpmIEWGA90tAL+iwPA08Ennyfoh6kGscOu2VY2sukBo6VVT5Uz 8g47hs3zUIkNw== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Normally, callers to handle_mm_fault() are supposed to check the vma->vm_flags first. hmm_range_fault() checks for VM_READ but doesn't check for VM_WRITE if the caller requests a page to be faulted in with write permission (via the hmm_range.pfns[] value). If the vma is write protected, this can result in an infinite loop: hmm_range_fault() walk_page_range() ... hmm_vma_walk_hole() hmm_vma_walk_hole_() hmm_vma_do_fault() handle_mm_fault(FAULT_FLAG_WRITE) /* returns VM_FAULT_WRITE */ /* returns -EBUSY */ /* returns -EBUSY */ /* returns -EBUSY */ /* loops on -EBUSY and range->valid */ Prevent this by checking for vma->vm_flags & VM_WRITE before calling handle_mm_fault(). Signed-off-by: Ralph Campbell --- mm/hmm.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/hmm.c b/mm/hmm.c index 29371485fe94..4882b83aeccb 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -292,6 +292,9 @@ static int hmm_vma_walk_hole_(unsigned long addr, unsig= ned long end, hmm_vma_walk->last =3D addr; i =3D (addr - range->start) >> PAGE_SHIFT; =20 + if (write_fault && walk->vma && !(walk->vma->vm_flags & VM_WRITE)) + return -EPERM; + for (; addr < end; addr +=3D PAGE_SIZE, i++) { pfns[i] =3D range->values[HMM_PFN_NONE]; if (fault || write_fault) { --=20 2.20.1