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=-18.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 CB639C433E6 for ; Tue, 2 Feb 2021 14:22:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8BEDE64DD6 for ; Tue, 2 Feb 2021 14:22:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234371AbhBBOW3 (ORCPT ); Tue, 2 Feb 2021 09:22:29 -0500 Received: from mail.kernel.org ([198.145.29.99]:49514 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234208AbhBBON0 (ORCPT ); Tue, 2 Feb 2021 09:13:26 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 020C964FB5; Tue, 2 Feb 2021 13:53:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1612273984; bh=w6g19S2WBt4INR8oiK1ZUQ1ESqkWehgIWisRg4kEjOA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Lpr6ubEzc9AJ7a8BV5luZjIu+3a6K5xOKkr5AuphXNDUjveiU2soDh3n9HfqnFY55 kHl+Aalp4z0Ye6XOZDov3nYYaRM6MOFtOEiBRI15oc9NKQsLBYV0R79I2cvKg4YnAt YyQCKvl3cRohALQP0E+uZkhKM3L5fSMDkTBFnk+s= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Josef Bacik , Jens Axboe Subject: [PATCH 4.19 01/37] nbd: freeze the queue while were adding connections Date: Tue, 2 Feb 2021 14:38:44 +0100 Message-Id: <20210202132942.964803997@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210202132942.915040339@linuxfoundation.org> References: <20210202132942.915040339@linuxfoundation.org> User-Agent: quilt/0.66 X-stable: review X-Patchwork-Hint: ignore 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: Josef Bacik commit b98e762e3d71e893b221f871825dc64694cfb258 upstream. When setting up a device, we can krealloc the config->socks array to add new sockets to the configuration. However if we happen to get a IO request in at this point even though we aren't setup we could hit a UAF, as we deref config->socks without any locking, assuming that the configuration was setup already and that ->socks is safe to access it as we have a reference on the configuration. But there's nothing really preventing IO from occurring at this point of the device setup, we don't want to incur the overhead of a lock to access ->socks when it will never change while the device is running. To fix this UAF scenario simply freeze the queue if we are adding sockets. This will protect us from this particular case without adding any additional overhead for the normal running case. Cc: stable@vger.kernel.org Signed-off-by: Josef Bacik Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- drivers/block/nbd.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -966,6 +966,12 @@ static int nbd_add_socket(struct nbd_dev if (!sock) return err; + /* + * We need to make sure we don't get any errant requests while we're + * reallocating the ->socks array. + */ + blk_mq_freeze_queue(nbd->disk->queue); + if (!netlink && !nbd->task_setup && !test_bit(NBD_BOUND, &config->runtime_flags)) nbd->task_setup = current; @@ -1004,10 +1010,12 @@ static int nbd_add_socket(struct nbd_dev nsock->cookie = 0; socks[config->num_connections++] = nsock; atomic_inc(&config->live_connections); + blk_mq_unfreeze_queue(nbd->disk->queue); return 0; put_socket: + blk_mq_unfreeze_queue(nbd->disk->queue); sockfd_put(sock); return err; }