From patchwork Wed Jul 21 09:38:31 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: 12390519 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=-15.8 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,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 E3AEAC636CE for ; Wed, 21 Jul 2021 09:59:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C046B6124B for ; Wed, 21 Jul 2021 09:59:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235879AbhGUJQc (ORCPT ); Wed, 21 Jul 2021 05:16:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46410 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236422AbhGUI6i (ORCPT ); Wed, 21 Jul 2021 04:58:38 -0400 Received: from mail-pg1-x536.google.com (mail-pg1-x536.google.com [IPv6:2607:f8b0:4864:20::536]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BE815C061766; Wed, 21 Jul 2021 02:39:07 -0700 (PDT) Received: by mail-pg1-x536.google.com with SMTP id y17so1306815pgf.12; Wed, 21 Jul 2021 02:39:07 -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=k2mLgBDMkGUQBCzSqER4QTCbdvyrdYf6Xh8AVOpZnfA=; b=ArZINa6/qI3WjclTauQmOlJBrbzAMYikrIoXzATfH4tpPwAuGtISWHbSimJ5bG5Kef xM5N1f9hVofqmrTgwtKgjPq5H8PB57RmQQCYGz1HTckWQ1KkqWH3jxLrmNNDMtNwf70w UxgOCyuWpqPL95r4xuG4CB3ClLuhG2suK2v0caTs2wzMt7BhjvV1zTQtsBSnbIQO5l2S F9Q6ZS3Cdp34UlAGmY0+pS+1ynGqgrHYkEpW6lhW8/Jgt0npqrKiRmuIZeyEHPljGqxx FFCIgbMqDov3n07kNA1QaZD/UkMKYQJXCPWdTspMTMAr7/v1f4m1zsuseWa4QMeYui+W Az/Q== 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=k2mLgBDMkGUQBCzSqER4QTCbdvyrdYf6Xh8AVOpZnfA=; b=hOcDxxYyEmCJcMiCXfO+3fUDBl2vVwcfS82B1tFF3vfbZSNOr7vhQ81fta1w6UMak9 FEog3zuSfhO9c4BNUpRJoPpbwbBSOQ4BBTF+Z/rKLmhu3mP464suyxjLdtX+kZXw23q5 mqZ2mHyu0TBoLKjUBhAuU82izvIEQoVPhJ2jHvKV1tw9HcrzryYqft3Kw3v39rdMGy2/ vHqr3eoN2stIgDIUXnDS0+NDvtt+8pSqL1cchNIDFyU/mbiAy6660GNeNUIBlEtos5FC 4AsFYoGnH9m9POS6rkGfNHWJmZfxADLNbrNAcRLjRAAJn+z3Z8PwsLmb0/pLKA3uAG6+ fraw== X-Gm-Message-State: AOAM533x9Qk30E54aqJP9LIJMkzg7KdJG8UAAMrAcavRIkFdqClwg7Vw NyPAZE2oK5xWFwOYmE80o24= X-Google-Smtp-Source: ABdhPJwBTejj1XHrX4y16hWCM4hlBtLGRRRXmK1BYT/mRVpTxnfWRRPZGaq1F2YsM8xhjWqOj3M4zg== X-Received: by 2002:a63:f40e:: with SMTP id g14mr35216908pgi.158.1626860347326; Wed, 21 Jul 2021 02:39:07 -0700 (PDT) Received: from localhost.localdomain ([118.200.190.93]) by smtp.gmail.com with ESMTPSA id j129sm27311956pfb.132.2021.07.21.02.39.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Jul 2021 02:39:06 -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, matthieu.baerts@tessares.net, stefan@datenfreihafen.org Cc: Desmond Cheong Zhi Xi , linux-bluetooth@vger.kernel.org, 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 v3 1/2] Bluetooth: fix inconsistent lock state in SCO Date: Wed, 21 Jul 2021 17:38:31 +0800 Message-Id: <20210721093832.78081-2-desmondcheongzx@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210721093832.78081-1-desmondcheongzx@gmail.com> References: <20210721093832.78081-1-desmondcheongzx@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org Syzbot reported an inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} lock usage in sco_conn_del and sco_sock_timeout that could lead to deadlocks. This inconsistent lock state can also happen in sco_conn_ready, rfcomm_connect_ind, and bt_accept_enqueue. The issue is that these functions take a spin lock on the socket with interrupts enabled, but sco_sock_timeout takes the lock in an IRQ context. This could lead to deadlocks: CPU0 ---- lock(slock-AF_BLUETOOTH-BTPROTO_SCO); lock(slock-AF_BLUETOOTH-BTPROTO_SCO); *** DEADLOCK *** We fix this by ensuring that local bh is disabled before calling bh_lock_sock. After doing this, we additionally need to protect sco_conn_lock by disabling local bh. This is necessary because sco_conn_del makes a call to sco_chan_del while holding on to the sock lock, and sco_chan_del itself makes a call to sco_conn_lock. If sco_conn_lock is held elsewhere with interrupts enabled, there could still be a slock-AF_BLUETOOTH-BTPROTO_SCO --> &conn->lock#2 lock inversion as follows: CPU0 CPU1 ---- ---- lock(&conn->lock#2); local_irq_disable(); lock(slock-AF_BLUETOOTH-BTPROTO_SCO); lock(&conn->lock#2); lock(slock-AF_BLUETOOTH-BTPROTO_SCO); *** DEADLOCK *** Although sco_conn_del disables local bh before calling sco_chan_del, we can still wrap the calls to sco_conn_lock in sco_chan_del, with local_bh_disable/enable as this pair of functions are reentrant. 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 | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c index 3bd41563f118..34f3419c3330 100644 --- a/net/bluetooth/sco.c +++ b/net/bluetooth/sco.c @@ -140,10 +140,12 @@ static void sco_chan_del(struct sock *sk, int err) BT_DBG("sk %p, conn %p, err %d", sk, conn, err); if (conn) { + local_bh_disable(); sco_conn_lock(conn); conn->sk = NULL; sco_pi(sk)->conn = NULL; sco_conn_unlock(conn); + local_bh_enable(); if (conn->hcon) hci_conn_drop(conn->hcon); @@ -167,16 +169,22 @@ static void sco_conn_del(struct hci_conn *hcon, int err) BT_DBG("hcon %p conn %p, err %d", hcon, conn, err); /* Kill socket */ + local_bh_disable(); sco_conn_lock(conn); sk = conn->sk; sco_conn_unlock(conn); + local_bh_enable(); if (sk) { sock_hold(sk); + + local_bh_disable(); bh_lock_sock(sk); sco_sock_clear_timer(sk); sco_chan_del(sk, err); bh_unlock_sock(sk); + local_bh_enable(); + sco_sock_kill(sk); sock_put(sk); } @@ -202,6 +210,7 @@ static int sco_chan_add(struct sco_conn *conn, struct sock *sk, { int err = 0; + local_bh_disable(); sco_conn_lock(conn); if (conn->sk) err = -EBUSY; @@ -209,6 +218,7 @@ static int sco_chan_add(struct sco_conn *conn, struct sock *sk, __sco_chan_add(conn, sk, parent); sco_conn_unlock(conn); + local_bh_enable(); return err; } @@ -303,9 +313,11 @@ static void sco_recv_frame(struct sco_conn *conn, struct sk_buff *skb) { struct sock *sk; + local_bh_disable(); sco_conn_lock(conn); sk = conn->sk; sco_conn_unlock(conn); + local_bh_enable(); if (!sk) goto drop; @@ -420,10 +432,12 @@ static void __sco_sock_close(struct sock *sk) if (sco_pi(sk)->conn->hcon) { sk->sk_state = BT_DISCONN; sco_sock_set_timer(sk, SCO_DISCONN_TIMEOUT); + local_bh_disable(); sco_conn_lock(sco_pi(sk)->conn); hci_conn_drop(sco_pi(sk)->conn->hcon); sco_pi(sk)->conn->hcon = NULL; sco_conn_unlock(sco_pi(sk)->conn); + local_bh_enable(); } else sco_chan_del(sk, ECONNRESET); break; @@ -1084,21 +1098,26 @@ static void sco_conn_ready(struct sco_conn *conn) if (sk) { sco_sock_clear_timer(sk); + local_bh_disable(); bh_lock_sock(sk); sk->sk_state = BT_CONNECTED; sk->sk_state_change(sk); bh_unlock_sock(sk); + local_bh_enable(); } else { + local_bh_disable(); sco_conn_lock(conn); if (!conn->hcon) { sco_conn_unlock(conn); + local_bh_enable(); return; } parent = sco_get_sock_listen(&conn->hcon->src); if (!parent) { sco_conn_unlock(conn); + local_bh_enable(); return; } @@ -1109,6 +1128,7 @@ static void sco_conn_ready(struct sco_conn *conn) if (!sk) { bh_unlock_sock(parent); sco_conn_unlock(conn); + local_bh_enable(); return; } @@ -1131,6 +1151,7 @@ static void sco_conn_ready(struct sco_conn *conn) bh_unlock_sock(parent); sco_conn_unlock(conn); + local_bh_enable(); } }