From patchwork Fri Oct 4 19:46:40 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: 11175255 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 2767613B1 for ; Fri, 4 Oct 2019 19:46:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0F3052084D for ; Fri, 4 Oct 2019 19:46:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729542AbfJDTql (ORCPT ); Fri, 4 Oct 2019 15:46:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60910 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727978AbfJDTql (ORCPT ); Fri, 4 Oct 2019 15:46:41 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 425C881129; Fri, 4 Oct 2019 19:46:41 +0000 (UTC) Received: from localhost.localdomain.com (ovpn-122-29.rdu2.redhat.com [10.10.122.29]) by smtp.corp.redhat.com (Postfix) with ESMTP id D93BE5D9DC; Fri, 4 Oct 2019 19:46:40 +0000 (UTC) From: Bill O'Donnell To: linux-xfs@vger.kernel.org Cc: darrick.wong@oracle.com Subject: [PATCH v5] xfs: assure zeroed memory buffers for certain kmem allocations Date: Fri, 4 Oct 2019 14:46:40 -0500 Message-Id: <20191004194640.17511-1-billodo@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Fri, 04 Oct 2019 19:46:41 +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 Reviewed-by: Darrick J. Wong --- v5: apply KM_ZERO for kmem_alloc_io calls in xfs_log.c and xfs_log_recover.c v4: use __GFP_ZERO as part of gfp_mask (instead of KM_ZERO) 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 | 12 +++++++++++- fs/xfs/xfs_log.c | 2 +- fs/xfs/xfs_log_recover.c | 2 +- 3 files changed, 13 insertions(+), 3 deletions(-) diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index 120ef99d09e8..5d0a68de5fa6 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -345,6 +345,15 @@ xfs_buf_allocate_memory( unsigned short page_count, i; xfs_off_t start, end; int error; + uint kmflag_mask = 0; + + /* + * assure zeroed buffer for non-read cases. + */ + if (!(flags & XBF_READ)) { + kmflag_mask |= KM_ZERO; + gfp_mask |= __GFP_ZERO; + } /* * for buffers that are contained within a single page, just allocate @@ -354,7 +363,8 @@ 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; diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c index a2beee9f74da..641d07f30a27 100644 --- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -1443,7 +1443,7 @@ xlog_alloc_log( prev_iclog = iclog; iclog->ic_data = kmem_alloc_io(log->l_iclog_size, align_mask, - KM_MAYFAIL); + KM_MAYFAIL | KM_ZERO); if (!iclog->ic_data) goto out_free_iclog; #ifdef DEBUG diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c index 508319039dce..c1a514ffff55 100644 --- a/fs/xfs/xfs_log_recover.c +++ b/fs/xfs/xfs_log_recover.c @@ -127,7 +127,7 @@ xlog_alloc_buffer( if (nbblks > 1 && log->l_sectBBsize > 1) nbblks += log->l_sectBBsize; nbblks = round_up(nbblks, log->l_sectBBsize); - return kmem_alloc_io(BBTOB(nbblks), align_mask, KM_MAYFAIL); + return kmem_alloc_io(BBTOB(nbblks), align_mask, KM_MAYFAIL | KM_ZERO); } /*