From patchwork Thu May 20 09:21:02 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 444157 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=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 C174BC43461 for ; Thu, 20 May 2021 10:51:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A6AFC61001 for ; Thu, 20 May 2021 10:51:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239171AbhETKwY (ORCPT ); Thu, 20 May 2021 06:52:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:48344 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238842AbhETKuV (ORCPT ); Thu, 20 May 2021 06:50:21 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0B67261CC9; Thu, 20 May 2021 09:59:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621504780; bh=ElteuhxU74EAMqjOjjz/72X/iO6FNABX35L6I2b60iQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rzVkGSao7eV9rgeN6lvoVkmybjeeccSfYODEgLzApAA/TlFKum3ulfYAKM1ZskOMW zTzpX9gmcUxBJPoHedNaxcHXLN6/e7+1IoVLqyq6a6UQ5iFy08anrioqLabZlVVi9G qINENeRG2MxOLvMRfYqRdCTprwRO3oirAmAYY4iI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lin Ma , Marcel Holtmann Subject: [PATCH 4.9 070/240] bluetooth: eliminate the potential race condition when removing the HCI controller Date: Thu, 20 May 2021 11:21:02 +0200 Message-Id: <20210520092111.028699218@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210520092108.587553970@linuxfoundation.org> References: <20210520092108.587553970@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Lin Ma commit e2cb6b891ad2b8caa9131e3be70f45243df82a80 upstream. There is a possible race condition vulnerability between issuing a HCI command and removing the cont. Specifically, functions hci_req_sync() and hci_dev_do_close() can race each other like below: thread-A in hci_req_sync() | thread-B in hci_dev_do_close() | hci_req_sync_lock(hdev); test_bit(HCI_UP, &hdev->flags); | ... | test_and_clear_bit(HCI_UP, &hdev->flags) hci_req_sync_lock(hdev); | | In this commit we alter the sequence in function hci_req_sync(). Hence, the thread-A cannot issue th. Signed-off-by: Lin Ma Cc: Marcel Holtmann Fixes: 7c6a329e4447 ("[Bluetooth] Fix regression from using default link policy") Signed-off-by: Greg Kroah-Hartman --- net/bluetooth/hci_request.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) --- a/net/bluetooth/hci_request.c +++ b/net/bluetooth/hci_request.c @@ -275,12 +275,16 @@ int hci_req_sync(struct hci_dev *hdev, i { int ret; - if (!test_bit(HCI_UP, &hdev->flags)) - return -ENETDOWN; - /* Serialize all requests */ hci_req_sync_lock(hdev); - ret = __hci_req_sync(hdev, req, opt, timeout, hci_status); + /* check the state after obtaing the lock to protect the HCI_UP + * against any races from hci_dev_do_close when the controller + * gets removed. + */ + if (test_bit(HCI_UP, &hdev->flags)) + ret = __hci_req_sync(hdev, req, opt, timeout, hci_status); + else + ret = -ENETDOWN; hci_req_sync_unlock(hdev); return ret;