From patchwork Thu Sep 19 15:01:54 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bill O'Donnell X-Patchwork-Id: 11152763 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8E0F514DB for ; Thu, 19 Sep 2019 15:01:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7692321929 for ; Thu, 19 Sep 2019 15:01:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390877AbfISPBz (ORCPT ); Thu, 19 Sep 2019 11:01:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42268 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389586AbfISPBz (ORCPT ); Thu, 19 Sep 2019 11:01:55 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6C1423083391 for ; Thu, 19 Sep 2019 15:01:55 +0000 (UTC) Received: from localhost.localdomain.com (ovpn-123-212.rdu2.redhat.com [10.10.123.212]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1EE5B6013A for ; Thu, 19 Sep 2019 15:01:55 +0000 (UTC) From: Bill O'Donnell To: linux-xfs@vger.kernel.org Subject: [PATCH v3] xfs: assure zeroed memory buffers for certain kmem allocations Date: Thu, 19 Sep 2019 10:01:54 -0500 Message-Id: <20190919150154.30302-1-billodo@redhat.com> In-Reply-To: <20190916153504.30809-1-billodo@redhat.com> References: <20190916153504.30809-1-billodo@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Thu, 19 Sep 2019 15:01:55 +0000 (UTC) Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org Guarantee zeroed memory buffers for cases where potential memory leak to disk can occur. In these cases, kmem_alloc is used and doesn't zero the buffer, opening the possibility of information leakage to disk. Use existing infrastucture (xfs_buf_allocate_memory) to obtain the already zeroed buffer from kernel memory. This solution avoids the performance issue that would occur if a wholesale change to replace kmem_alloc with kmem_zalloc was done. Signed-off-by: Bill O'Donnell --- v3: remove XBF_ZERO flag, and instead use XBF_READ flag only. v2: zeroed buffer not required for XBF_READ case. Correct placement and rename the XBF_ZERO flag. fs/xfs/xfs_buf.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index 120ef99d09e8..6fbe63f34a68 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -345,6 +345,10 @@ xfs_buf_allocate_memory( unsigned short page_count, i; xfs_off_t start, end; int error; + uint kmflag_mask = 0; + + if (!(flags & XBF_READ)) + kmflag_mask |= KM_ZERO; /* * for buffers that are contained within a single page, just allocate @@ -354,7 +358,8 @@ xfs_buf_allocate_memory( size = BBTOB(bp->b_length); if (size < PAGE_SIZE) { int align_mask = xfs_buftarg_dma_alignment(bp->b_target); - bp->b_addr = kmem_alloc_io(size, align_mask, KM_NOFS); + bp->b_addr = kmem_alloc_io(size, align_mask, + KM_NOFS | kmflag_mask); if (!bp->b_addr) { /* low memory - use alloc_page loop instead */ goto use_alloc_page; @@ -391,7 +396,7 @@ xfs_buf_allocate_memory( struct page *page; uint retries = 0; retry: - page = alloc_page(gfp_mask); + page = alloc_page(gfp_mask | kmflag_mask); if (unlikely(page == NULL)) { if (flags & XBF_READ_AHEAD) { bp->b_page_count = i;