From patchwork Wed Mar 24 18:47:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Winkler X-Patchwork-Id: 408644 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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, 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, USER_IN_DEF_DKIM_WL 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 10825C433E0 for ; Wed, 24 Mar 2021 18:48:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E24CB61A27 for ; Wed, 24 Mar 2021 18:48:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237653AbhCXSrg (ORCPT ); Wed, 24 Mar 2021 14:47:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49742 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237677AbhCXSrJ (ORCPT ); Wed, 24 Mar 2021 14:47:09 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A6077C0613DE for ; Wed, 24 Mar 2021 11:47:08 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id 131so3350436ybp.16 for ; Wed, 24 Mar 2021 11:47:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=rKcNbR+LxTP4j4KG6QhvAtJ90pK5ENJOnzBCgg91Onk=; b=tHmA+b14JUxfjas7gHzGU6el3u3kffAUHUkD+sPuAhvVTGZmCTtIEJYIH1lxofX4qA Fng0ME678PGbmGlVLsIfQgNeZz6r6QSH542Ex82lanWrbWfn5G9aUYLoppQDYIjlO9aD x5HrVs0t+AgFqfePObi9np1MxOJObRbzom4bWTjbV/TcSu4i0ACNCJCG9fwDq2k2cKv2 EjW1sPVQcMF/hPRN+lVWQoocH/B5UJK0T9jaeM1+ofq8yESoDPtECfhdsVW22pfdn6tc auPPqHm6ZeoP0dveluUbzuc9a5aHJrlyHpbkZiXIfGaMZ0inBit7rrZCSUJ+NawQWlry GVaA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=rKcNbR+LxTP4j4KG6QhvAtJ90pK5ENJOnzBCgg91Onk=; b=HwLM4UJySkhsirf1OzAHyERO56OPY6fvv2fk/Kd5KPzvUZuQN/rsPtiXk0SRsJ+0uO JMhRQer3gK/ASnX0tsSLUWgvpZhiOgUjWyKGxE+PHbAnZsL2d+1v7LEb9zeYu60p+ncw fLfies4xlOtPYQyjWjrCW+pAswDwnFBfstaDhb6McyGQFYtl54S8EMevLDpKGG/Ts6ar aVsDUToUClziVzT5jy7V4TjPmaLdlt0/D9x89ym+qseubNMZrAZLk8omjS9jLxKz9JNQ reoIVLRT+eqwVZ8UDYjQluEwXaRJo+0MMd8fNJyZT4XKKm998BA9YcM4v1ULHnJ6VecP GFuw== X-Gm-Message-State: AOAM530VumkhZpSXpCO17mSra9arb7+6Smc2WqsR8ZxSuZU4XoCl4A8n RuOZhdd4rYWVCnq/OGenGdqLBbaNzb3s1ZwfXQ4z X-Google-Smtp-Source: ABdhPJw5jhML1zb+OVbUM2/vBIFd6z6LjwoP90Rg2G6aIKnjRPTyyQjQDggU3LK8VY9QFoCVintXXoK5ZaOWnp3RTHlh X-Received: from danielwinkler-linux.mtv.corp.google.com ([2620:15c:202:201:f18d:a314:46c6:7a97]) (user=danielwinkler job=sendgmr) by 2002:a25:ba10:: with SMTP id t16mr6021053ybg.222.1616611627661; Wed, 24 Mar 2021 11:47:07 -0700 (PDT) Date: Wed, 24 Mar 2021 11:47:03 -0700 Message-Id: <20210324114645.v2.1.I53e6be1f7df0be198b7e55ae9fc45c7f5760132d@changeid> Mime-Version: 1.0 X-Mailer: git-send-email 2.31.0.291.g576ba9dcdaf-goog Subject: [PATCH v2] Bluetooth: Always call advertising disable before setting params From: Daniel Winkler To: linux-bluetooth@vger.kernel.org Cc: chromeos-bluetooth-upstreaming@chromium.org, Daniel Winkler , Miao-chen Chou , "David S. Miller" , Jakub Kicinski , Johan Hedberg , Luiz Augusto von Dentz , Marcel Holtmann , linux-kernel@vger.kernel.org, netdev@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org In __hci_req_enable_advertising, the HCI_LE_ADV hdev flag is temporarily cleared to allow the random address to be set, which exposes a race condition when an advertisement is configured immediately (<10ms) after software rotation starts to refresh an advertisement. In normal operation, the HCI_LE_ADV flag is updated as follows: 1. adv_timeout_expire is called, HCI_LE_ADV gets cleared in __hci_req_enable_advertising, but hci_req configures an enable request 2. hci_req is run, enable callback re-sets HCI_LE_ADV flag However, in this race condition, the following occurs: 1. adv_timeout_expire is called, HCI_LE_ADV gets cleared in __hci_req_enable_advertising, but hci_req configures an enable request 2. add_advertising is called, which also calls __hci_req_enable_advertising. Because HCI_LE_ADV was cleared in Step 1, no "disable" command is queued. 3. hci_req for adv_timeout_expire is run, which enables advertising and re-sets HCI_LE_ADV 4. hci_req for add_advertising is run, but because no "disable" command was queued, we try to set advertising parameters while advertising is active, causing a Command Disallowed error, failing the registration. To resolve the issue, this patch removes the check for the HCI_LE_ADV flag, and always queues the "disable" request, since HCI_LE_ADV could be very temporarily out-of-sync. According to the spec, there is no harm in calling "disable" when advertising is not active. An example trace showing the HCI error in setting advertising parameters is included below, with some notes annotating the states I mentioned above: @ MGMT Command: Add Ext Adv.. (0x0055) plen 35 {0x0001} [hci0]04:05.884 Instance: 3 Advertising data length: 24 16-bit Service UUIDs (complete): 2 entries Location and Navigation (0x1819) Phone Alert Status Service (0x180e) Company: not assigned (65283) Data: 3a3b3c3d3e Service Data (UUID 0x9993): 3132333435 Scan response length: 0 @ MGMT Event: Advertising Ad.. (0x0023) plen 1 {0x0005} [hci0]04:05.885 Instance: 3 === adv_timeout_expire request starts running. This request was created before our add advertising request > HCI Event: Command Complete (0x0e) plen 4 #220 [hci0]04:05.993 LE Set Advertising Data (0x08|0x0008) ncmd 1 Status: Success (0x00) < HCI Command: LE Set Scan.. (0x08|0x0009) plen 32 #221 [hci0]04:05.993 Length: 24 Service Data (UUID 0xabcd): 161718191a1b1c1d1e1f2021222324252627 > HCI Event: Command Complete (0x0e) plen 4 #222 [hci0]04:05.995 LE Set Scan Response Data (0x08|0x0009) ncmd 1 Status: Success (0x00) < HCI Command: LE Set Adver.. (0x08|0x000a) plen 1 #223 [hci0]04:05.995 Advertising: Disabled (0x00) > HCI Event: Command Complete (0x0e) plen 4 #224 [hci0]04:05.997 LE Set Advertise Enable (0x08|0x000a) ncmd 1 Status: Success (0x00) < HCI Command: LE Set Adve.. (0x08|0x0006) plen 15 #225 [hci0]04:05.997 Min advertising interval: 200.000 msec (0x0140) Max advertising interval: 200.000 msec (0x0140) Type: Connectable undirected - ADV_IND (0x00) Own address type: Public (0x00) Direct address type: Public (0x00) Direct address: 00:00:00:00:00:00 (OUI 00-00-00) Channel map: 37, 38, 39 (0x07) Filter policy: Allow Scan Request, Connect from Any (0x00) > HCI Event: Command Complete (0x0e) plen 4 #226 [hci0]04:05.998 LE Set Advertising Parameters (0x08|0x0006) ncmd 1 Status: Success (0x00) < HCI Command: LE Set Adver.. (0x08|0x000a) plen 1 #227 [hci0]04:05.999 Advertising: Enabled (0x01) > HCI Event: Command Complete (0x0e) plen 4 #228 [hci0]04:06.000 LE Set Advertise Enable (0x08|0x000a) ncmd 1 Status: Success (0x00) === Our new add_advertising request starts running < HCI Command: Read Local N.. (0x03|0x0014) plen 0 #229 [hci0]04:06.001 > HCI Event: Command Complete (0x0e) plen 252 #230 [hci0]04:06.005 Read Local Name (0x03|0x0014) ncmd 1 Status: Success (0x00) Name: Chromebook_FB3D === Although the controller is advertising, no disable command is sent < HCI Command: LE Set Adve.. (0x08|0x0006) plen 15 #231 [hci0]04:06.005 Min advertising interval: 200.000 msec (0x0140) Max advertising interval: 200.000 msec (0x0140) Type: Connectable undirected - ADV_IND (0x00) Own address type: Public (0x00) Direct address type: Public (0x00) Direct address: 00:00:00:00:00:00 (OUI 00-00-00) Channel map: 37, 38, 39 (0x07) Filter policy: Allow Scan Request, Connect from Any (0x00) > HCI Event: Command Complete (0x0e) plen 4 #232 [hci0]04:06.005 LE Set Advertising Parameters (0x08|0x0006) ncmd 1 Status: Command Disallowed (0x0c) Reviewed-by: Miao-chen Chou Signed-off-by: Daniel Winkler --- Changes in v2: - Added btmon snippet showing HCI command failure net/bluetooth/hci_request.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/bluetooth/hci_request.c b/net/bluetooth/hci_request.c index 8ace5d34b01efe..2b4b99f4cedf21 100644 --- a/net/bluetooth/hci_request.c +++ b/net/bluetooth/hci_request.c @@ -1547,8 +1547,10 @@ void __hci_req_enable_advertising(struct hci_request *req) if (!is_advertising_allowed(hdev, connectable)) return; - if (hci_dev_test_flag(hdev, HCI_LE_ADV)) - __hci_req_disable_advertising(req); + /* Request that the controller stop advertising. This can be called + * whether or not there is an active advertisement. + */ + __hci_req_disable_advertising(req); /* Clear the HCI_LE_ADV bit temporarily so that the * hci_update_random_address knows that it's safe to go ahead