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=-9.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 49EF6C43387 for ; Fri, 14 Dec 2018 20:32:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 89D6A2080F for ; Fri, 14 Dec 2018 20:32:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1544819550; bh=pRgCTIOsiEvEuttqrH8YrexzH/2Tl0/O+NJvbjuss00=; h=From:To:Cc:Subject:Date:List-ID:From; b=MXZb0r1Yi6Pb8oyVcjSiJpGAfyWFrcT+6/sH2kifUHzc+fgo+1gukanplnEdVDDvf 4O+xshrks2HpcqtmOYYEzEld/xTFPgRV2QNlw9NKy18zw9SJxfkK/1DUcO3TGk6w57 5GLuht9t52EoVB5iZJ44VZAT/WyHq8Dox2AVkMcc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730731AbeLNUc3 (ORCPT ); Fri, 14 Dec 2018 15:32:29 -0500 Received: from mail.kernel.org ([198.145.29.99]:36942 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730714AbeLNUc3 (ORCPT ); Fri, 14 Dec 2018 15:32:29 -0500 Received: from localhost (unknown [104.132.0.93]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 113EB2080F; Fri, 14 Dec 2018 20:32:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1544819549; bh=pRgCTIOsiEvEuttqrH8YrexzH/2Tl0/O+NJvbjuss00=; h=From:To:Cc:Subject:Date:From; b=zYZchJJ/wTQAq2nqnpMKRyi/o/mWnQnaIy/hj606dBPVi+0mUiZTPrlyr+O5j4KO2 INVfXqkD+A84fA+ooyfeVIOF6GYlZRX1X1nwn9PMqTYHEIa7vALfLPLFidfmwnJPEn PVLFZAgVuwdxmzynryAXyN8JKLtTjr1L/KwfM94g= From: Jaegeuk Kim To: linux-kernel@vger.kernel.org Cc: Jaegeuk Kim , Jens Axboe , linux-block@vger.kernel.org Subject: [PATCH] loop: drop caches if offset is changed Date: Fri, 14 Dec 2018 12:32:23 -0800 Message-Id: <20181214203223.7063-1-jaegeuk@kernel.org> X-Mailer: git-send-email 2.19.0.605.g01d371f741-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org If we don't drop caches used in old offset, we can get old data from new offset, which gives unexpected data to user. Martijn found a loopback bug in the below scenario. 1) LOOP_SET_FD loads first two pages on loop file 2) LOOP_SET_STATUS64 changes the offset on the loop file 3) mount is failed due to the cached pages having wrong superblock This patch drops caches when we change lo->offset. Cc: Jens Axboe Cc: linux-block@vger.kernel.org Reported-by: Martijn Coenen Signed-off-by: Jaegeuk Kim --- drivers/block/loop.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index cb0cc8685076..f073a3f1a7cd 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1154,6 +1154,12 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) if (lo->lo_offset != info->lo_offset || lo->lo_sizelimit != info->lo_sizelimit) { + struct block_device *bdev = lo->lo_device; + + /* drop stale caches used in old offset */ + sync_blockdev(bdev); + kill_bdev(bdev); + if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit)) { err = -EFBIG; goto exit; -- 2.19.0.605.g01d371f741-goog