From patchwork Wed Sep 18 15:47:33 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: 11150609 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 793B814E5 for ; Wed, 18 Sep 2019 15:47:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 62582206C2 for ; Wed, 18 Sep 2019 15:47:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731765AbfIRPre (ORCPT ); Wed, 18 Sep 2019 11:47:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44538 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728248AbfIRPre (ORCPT ); Wed, 18 Sep 2019 11:47:34 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 659AA3082B4B; Wed, 18 Sep 2019 15:47:34 +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 05CBE19C6A; Wed, 18 Sep 2019 15:47:33 +0000 (UTC) From: Bill O'Donnell To: linux-xfs@vger.kernel.org Cc: darrick.wong@oracle.com Subject: [PATCH v2] xfs: assure zeroed memory buffers for certain kmem allocations Date: Wed, 18 Sep 2019 10:47:33 -0500 Message-Id: <20190918154733.24355-1-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 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.45]); Wed, 18 Sep 2019 15:47:34 +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. Introduce a xfs_buf_flag, XBF_ZERO, to indicate a request for a zeroed buffer, and 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 --- v2: zeroed buffer not required for XBF_READ case. Correct placement and rename the XBF_ZERO flag. fs/xfs/xfs_buf.c | 9 +++++++-- fs/xfs/xfs_buf.h | 2 ++ fs/xfs/xfs_trans_buf.c | 2 ++ 3 files changed, 11 insertions(+), 2 deletions(-) diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index 120ef99d09e8..0d96efff451e 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_ZERO) && !(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; diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h index f6ce17d8d848..dccdd653c9dc 100644 --- a/fs/xfs/xfs_buf.h +++ b/fs/xfs/xfs_buf.h @@ -33,6 +33,7 @@ /* flags used only as arguments to access routines */ #define XBF_TRYLOCK (1 << 16)/* lock requested, but do not wait */ #define XBF_UNMAPPED (1 << 17)/* do not map the buffer */ +#define XBF_ZERO (1 << 18)/* zeroed buffer required */ /* flags used only internally */ #define _XBF_PAGES (1 << 20)/* backed by refcounted pages */ @@ -52,6 +53,7 @@ typedef unsigned int xfs_buf_flags_t; { XBF_WRITE_FAIL, "WRITE_FAIL" }, \ { XBF_TRYLOCK, "TRYLOCK" }, /* should never be set */\ { XBF_UNMAPPED, "UNMAPPED" }, /* ditto */\ + { XBF_ZERO, "KMEM_ZERO" }, \ { _XBF_PAGES, "PAGES" }, \ { _XBF_KMEM, "KMEM" }, \ { _XBF_DELWRI_Q, "DELWRI_Q" } diff --git a/fs/xfs/xfs_trans_buf.c b/fs/xfs/xfs_trans_buf.c index b5b3a78ef31c..087d413c1490 100644 --- a/fs/xfs/xfs_trans_buf.c +++ b/fs/xfs/xfs_trans_buf.c @@ -123,6 +123,8 @@ xfs_trans_get_buf_map( xfs_buf_t *bp; struct xfs_buf_log_item *bip; + flags |= XBF_ZERO; + if (!tp) return xfs_buf_get_map(target, map, nmaps, flags);