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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 86456C04FF3 for ; Mon, 24 May 2021 15:47:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 67DDE619A7 for ; Mon, 24 May 2021 15:47:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233150AbhEXPsn (ORCPT ); Mon, 24 May 2021 11:48:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:58234 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233751AbhEXPmL (ORCPT ); Mon, 24 May 2021 11:42:11 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C2BB6613AD; Mon, 24 May 2021 15:34:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621870499; bh=cCJCMC36Ge3NvLa2sMCwovOSbnmUC5nuuXymeLcvdQs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=coxmkF7lnLZPDD/Gy2UvMVkdCisbB6yqEsvZmA/eE3GQqIk1YjGpJdH4hD9OqqX7s dP2eUXqcOjuWEzDTJ+BvdJZ9qntNVunuvi+vHq+ca4UVwiEN7dy+0uE8nVEoOygCuj gadECb9CImmGdFuxSDC7n2gabOPD5lY2BSrxxMRw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mikulas Patocka , Mike Snitzer Subject: [PATCH 4.19 24/49] dm snapshot: fix crash with transient storage and zero chunk size Date: Mon, 24 May 2021 17:25:35 +0200 Message-Id: <20210524152325.158126942@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210524152324.382084875@linuxfoundation.org> References: <20210524152324.382084875@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mikulas Patocka commit c699a0db2d62e3bbb7f0bf35c87edbc8d23e3062 upstream. The following commands will crash the kernel: modprobe brd rd_size=1048576 dmsetup create o --table "0 `blockdev --getsize /dev/ram0` snapshot-origin /dev/ram0" dmsetup create s --table "0 `blockdev --getsize /dev/ram0` snapshot /dev/ram0 /dev/ram1 N 0" The reason is that when we test for zero chunk size, we jump to the label bad_read_metadata without setting the "r" variable. The function snapshot_ctr destroys all the structures and then exits with "r == 0". The kernel then crashes because it falsely believes that snapshot_ctr succeeded. In order to fix the bug, we set the variable "r" to -EINVAL. Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- drivers/md/dm-snap.c | 1 + 1 file changed, 1 insertion(+) --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -1285,6 +1285,7 @@ static int snapshot_ctr(struct dm_target if (!s->store->chunk_size) { ti->error = "Chunk size not set"; + r = -EINVAL; goto bad_read_metadata; }