From patchwork Thu Nov 29 06:00:59 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sasha Levin X-Patchwork-Id: 10703983 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 33AD714BD for ; Thu, 29 Nov 2018 06:09:18 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 265AA2E663 for ; Thu, 29 Nov 2018 06:09:18 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1A05C2E67F; Thu, 29 Nov 2018 06:09:18 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BC6F72E663 for ; Thu, 29 Nov 2018 06:09:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728806AbeK2RG5 (ORCPT ); Thu, 29 Nov 2018 12:06:57 -0500 Received: from mail.kernel.org ([198.145.29.99]:43800 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728459AbeK2RG4 (ORCPT ); Thu, 29 Nov 2018 12:06:56 -0500 Received: from sasha-vm.mshome.net (unknown [37.142.5.207]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id CF04C213A2; Thu, 29 Nov 2018 06:02:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1543471365; bh=Y2DGkWayWdKe5u1caSXSPraCZVXWFyu9URYJEP3L+Lk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EQOo9akyJSzPu06aQHvTLW/GlZtT1V6ObTwR/gCaUioSiodG44WisJf9p1oFGY2Gw 1Vf/Eh8430IFlgxFVq82x7gAYDOrubQJoJqTcHIrvgEg44jK8cPlvXVrHkylvta4w1 +eSLAIeJkraW2HPTc9gDTiPnLyvbsFnauEZ2QXaA= From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Dave Chinner , "Darrick J . Wong" , Sasha Levin , linux-fsdevel@vger.kernel.org Subject: [PATCH AUTOSEL 4.14 25/35] iomap: sub-block dio needs to zeroout beyond EOF Date: Thu, 29 Nov 2018 01:00:59 -0500 Message-Id: <20181129060110.159878-25-sashal@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181129060110.159878-1-sashal@kernel.org> References: <20181129060110.159878-1-sashal@kernel.org> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Dave Chinner [ Upstream commit b450672fb66b4a991a5b55ee24209ac7ae7690ce ] If we are doing sub-block dio that extends EOF, we need to zero the unused tail of the block to initialise the data in it it. If we do not zero the tail of the block, then an immediate mmap read of the EOF block will expose stale data beyond EOF to userspace. Found with fsx running sub-block DIO sizes vs MAPREAD/MAPWRITE operations. Fix this by detecting if the end of the DIO write is beyond EOF and zeroing the tail if necessary. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong Signed-off-by: Sasha Levin --- fs/iomap.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/iomap.c b/fs/iomap.c index 8f7673a69273..407efdae3978 100644 --- a/fs/iomap.c +++ b/fs/iomap.c @@ -940,7 +940,14 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length, dio->submit.cookie = submit_bio(bio); } while (nr_pages); - if (need_zeroout) { + /* + * We need to zeroout the tail of a sub-block write if the extent type + * requires zeroing or the write extends beyond EOF. If we don't zero + * the block tail in the latter case, we can expose stale data via mmap + * reads of the EOF block. + */ + if (need_zeroout || + ((dio->flags & IOMAP_DIO_WRITE) && pos >= i_size_read(inode))) { /* zero out from the end of the write to the end of the block */ pad = pos & (fs_block_size - 1); if (pad)