From patchwork Wed Aug 4 11:03:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Desmond Cheong Zhi Xi X-Patchwork-Id: 492770 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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, 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 5D5E7C4338F for ; Wed, 4 Aug 2021 11:03:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3E56F60F43 for ; Wed, 4 Aug 2021 11:03:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237761AbhHDLEE (ORCPT ); Wed, 4 Aug 2021 07:04:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35910 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237728AbhHDLED (ORCPT ); Wed, 4 Aug 2021 07:04:03 -0400 Received: from mail-pj1-x1034.google.com (mail-pj1-x1034.google.com [IPv6:2607:f8b0:4864:20::1034]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DB574C0613D5; Wed, 4 Aug 2021 04:03:50 -0700 (PDT) Received: by mail-pj1-x1034.google.com with SMTP id m10-20020a17090a34cab0290176b52c60ddso2975962pjf.4; Wed, 04 Aug 2021 04:03:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=srAeYY/EiQIT3OULRf8vlai9yqHxF+kaop05ae2z79I=; b=RGgUEIqv7EX3sOd8lMSiTQDivsxOgCMUFZDXh5+/jjewhAEgrysmVO+ACv84Gf2w+A nQvFXo5L5BeKS/AclyuD/jDVzlU8JHSUx4LkDfkP7IJXcPbZ/iswMHVf1PeLe70q2To6 0njJsUWQCZxsr3L0PIe49RDhHRk+f7qhlKmtQ0la10XXrC2nWaK5lLP4kaUyskd9M7vU PsAbUjFV6XCKlq9spLCty/nSROfI3o8y38vWlv+3ffgaNpczEc3OK1XOje8itSD3U03z diDle0TVvD0uA08W8tWF1IKt+efuaEvVqhyLK7YpVS+wm6pi44fQTcyvrg9wkfNG+ZLj 1s9Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=srAeYY/EiQIT3OULRf8vlai9yqHxF+kaop05ae2z79I=; b=T60x0ZgDShcNkuGbXjz86CShLXYgULZaNbMePPKDao3XY8i5ZOB4PBF+Z0lBNd3+Nr bkKwsRd+7l2z9TTUGAv14ShN5/Ga1NlsdIVSjB1GieClg8cQ9Lc11nqtSMeH/iOblsgs UtaZjuYnig4/wo6Zrw/ce2edlrKHwxJ2lVvCPYrYCp546YBYBJ7ILdBIX/gGsDFbLEHv MFUTRrmWAfmUypk6f6qJFJCOCNLCIrVerF1VeCNUyxT6NQql+4U42r9Hwb3Xpa8c3Z4K IBZRDgG15H9Eg5jX/Tcpt2nuMDKQWof7ak69FnUkcienvYN1C5HflWKr0o2gROZLQUhy 3RVA== X-Gm-Message-State: AOAM533XhWvI8om8WmY6WOqtZKHsRUkH6htGI/bUw3sxkXm1SlRi7kD7 lOo881IeEHU2TuGo2ER+Yfs= X-Google-Smtp-Source: ABdhPJw+OpqNnmqZmZ5BJkWvuLH5QpMKkTC47+FumpiJAWxcQOjVU/x/c2N0mXuzUKoSrM9tSOIZlw== X-Received: by 2002:a17:90a:c57:: with SMTP id u23mr9270081pje.186.1628075030416; Wed, 04 Aug 2021 04:03:50 -0700 (PDT) Received: from localhost.localdomain ([118.200.190.93]) by smtp.gmail.com with ESMTPSA id k4sm2206147pjs.55.2021.08.04.04.03.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Aug 2021 04:03:50 -0700 (PDT) From: Desmond Cheong Zhi Xi To: marcel@holtmann.org, johan.hedberg@gmail.com, luiz.dentz@gmail.com, davem@davemloft.net, kuba@kernel.org, sudipm.mukherjee@gmail.com Cc: Desmond Cheong Zhi Xi , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, gregkh@linuxfoundation.org, linux-kernel-mentees@lists.linuxfoundation.org, syzbot+2f6d7c28bb4bf7e82060@syzkaller.appspotmail.com Subject: [PATCH v5 1/6] Bluetooth: schedule SCO timeouts with delayed_work Date: Wed, 4 Aug 2021 19:03:03 +0800 Message-Id: <20210804110308.910744-2-desmondcheongzx@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210804110308.910744-1-desmondcheongzx@gmail.com> References: <20210804110308.910744-1-desmondcheongzx@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org struct sock.sk_timer should be used as a sock cleanup timer. However, SCO uses it to implement sock timeouts. This causes issues because struct sock.sk_timer's callback is run in an IRQ context, and the timer callback function sco_sock_timeout takes a spin lock on the socket. However, other functions such as sco_conn_del and sco_conn_ready take the spin lock with interrupts enabled. This inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} lock usage could lead to deadlocks as reported by Syzbot [1]: CPU0 ---- lock(slock-AF_BLUETOOTH-BTPROTO_SCO); lock(slock-AF_BLUETOOTH-BTPROTO_SCO); To fix this, we use delayed work to implement SCO sock timouts instead. This allows us to avoid taking the spin lock on the socket in an IRQ context, and corrects the misuse of struct sock.sk_timer. As a note, cancel_delayed_work is used instead of cancel_delayed_work_sync in sco_sock_set_timer and sco_sock_clear_timer to avoid a deadlock. In the future, the call to bh_lock_sock inside sco_sock_timeout should be changed to lock_sock to synchronize with other functions using lock_sock. However, since sco_sock_set_timer and sco_sock_clear_timer are sometimes called under the locked socket (in sco_connect and __sco_sock_close), cancel_delayed_work_sync might cause them to sleep until an sco_sock_timeout that has started finishes running. But sco_sock_timeout would also sleep until it can grab the lock_sock. Using cancel_delayed_work is fine because sco_sock_timeout does not change from run to run, hence there is no functional difference between: 1. waiting for a timeout to finish running before scheduling another timeout 2. scheduling another timeout while a timeout is running. Link: https://syzkaller.appspot.com/bug?id=9089d89de0502e120f234ca0fc8a703f7368b31e [1] Reported-by: syzbot+2f6d7c28bb4bf7e82060@syzkaller.appspotmail.com Tested-by: syzbot+2f6d7c28bb4bf7e82060@syzkaller.appspotmail.com Signed-off-by: Desmond Cheong Zhi Xi --- net/bluetooth/sco.c | 41 +++++++++++++++++++++++++++++++++++------ 1 file changed, 35 insertions(+), 6 deletions(-) diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c index ffa2a77a3e4c..89cb987ca9eb 100644 --- a/net/bluetooth/sco.c +++ b/net/bluetooth/sco.c @@ -48,6 +48,8 @@ struct sco_conn { spinlock_t lock; struct sock *sk; + struct delayed_work timeout_work; + unsigned int mtu; }; @@ -74,9 +76,20 @@ struct sco_pinfo { #define SCO_CONN_TIMEOUT (HZ * 40) #define SCO_DISCONN_TIMEOUT (HZ * 2) -static void sco_sock_timeout(struct timer_list *t) +static void sco_sock_timeout(struct work_struct *work) { - struct sock *sk = from_timer(sk, t, sk_timer); + struct sco_conn *conn = container_of(work, struct sco_conn, + timeout_work.work); + struct sock *sk; + + sco_conn_lock(conn); + sk = conn->sk; + if (sk) + sock_hold(sk); + sco_conn_unlock(conn); + + if (!sk) + return; BT_DBG("sock %p state %d", sk, sk->sk_state); @@ -91,14 +104,27 @@ static void sco_sock_timeout(struct timer_list *t) static void sco_sock_set_timer(struct sock *sk, long timeout) { + struct delayed_work *work; + + if (!sco_pi(sk)->conn) + return; + work = &sco_pi(sk)->conn->timeout_work; + BT_DBG("sock %p state %d timeout %ld", sk, sk->sk_state, timeout); - sk_reset_timer(sk, &sk->sk_timer, jiffies + timeout); + cancel_delayed_work(work); + schedule_delayed_work(work, timeout); } static void sco_sock_clear_timer(struct sock *sk) { + struct delayed_work *work; + + if (!sco_pi(sk)->conn) + return; + work = &sco_pi(sk)->conn->timeout_work; + BT_DBG("sock %p state %d", sk, sk->sk_state); - sk_stop_timer(sk, &sk->sk_timer); + cancel_delayed_work(work); } /* ---- SCO connections ---- */ @@ -179,6 +205,9 @@ static void sco_conn_del(struct hci_conn *hcon, int err) bh_unlock_sock(sk); sco_sock_kill(sk); sock_put(sk); + + /* Ensure no more work items will run before freeing conn. */ + cancel_delayed_work_sync(&conn->timeout_work); } hcon->sco_data = NULL; @@ -193,6 +222,8 @@ static void __sco_chan_add(struct sco_conn *conn, struct sock *sk, sco_pi(sk)->conn = conn; conn->sk = sk; + INIT_DELAYED_WORK(&conn->timeout_work, sco_sock_timeout); + if (parent) bt_accept_enqueue(parent, sk, true); } @@ -500,8 +531,6 @@ static struct sock *sco_sock_alloc(struct net *net, struct socket *sock, sco_pi(sk)->setting = BT_VOICE_CVSD_16BIT; - timer_setup(&sk->sk_timer, sco_sock_timeout, 0); - bt_sock_link(&sco_sk_list, sk); return sk; }