From patchwork Tue Jul 13 16:28:38 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: 12374507 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=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 56259C07E95 for ; Tue, 13 Jul 2021 16:29:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 38A40610C7 for ; Tue, 13 Jul 2021 16:29:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229604AbhGMQcF (ORCPT ); Tue, 13 Jul 2021 12:32:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43892 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229437AbhGMQcE (ORCPT ); Tue, 13 Jul 2021 12:32:04 -0400 Received: from mail-pj1-x1032.google.com (mail-pj1-x1032.google.com [IPv6:2607:f8b0:4864:20::1032]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D1375C0613DD; Tue, 13 Jul 2021 09:29:13 -0700 (PDT) Received: by mail-pj1-x1032.google.com with SMTP id b5-20020a17090a9905b029016fc06f6c5bso2464423pjp.5; Tue, 13 Jul 2021 09:29:13 -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:mime-version :content-transfer-encoding; bh=0if1JKGz6Y+FvBAbIJIXUcoRPTBbCA20QOj+Wr5C6ZA=; b=oDvHV80APNi2CCXFUVu82VLZOUFwYr5tsWH4aMZJ46xkF2BXqKfPcpLgYo10OiQ1KN MdFS/GxucV+VTgbkIwW03WFOAxWHIB1ABVwtpgXZ+qKgBV6J/Y7LhKIwe1aK2J6mpDaB iKHkRHZUzdXV9k3dfs/WitHRz0MRncWxfNT765ztasMS8E+uVjLtjd3QehJNy+tioGsS b/pA3rDNy9O7WNTTab5OwJWRvKGUqjbsb9YG7NcxvxLbgathM2Mr7dLuw3ooD6c7GV5o 2rz8HJ8b/00YeYIx/gHH6npnpGk/N7fuqaOaIKi5pyf6qvpyG5QJzbG25nMtWmwkX/// NQzg== 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:mime-version :content-transfer-encoding; bh=0if1JKGz6Y+FvBAbIJIXUcoRPTBbCA20QOj+Wr5C6ZA=; b=DsFLWScx+PmMKRA2YKchsQ6/hV60daObDjWIGg17xM/AI5/tJ+i/O6Q9DBX232wxzY 0rHMCJ4jjwQiZypi4Z/Ov+ihWN1UE3S9nuRSLFA3BYfdNqnI8oS0F1JpiFeoWQxqQ13f bWvDhjCskLT8yI1+UfwUIjYWXfI/holbaK+8rzE5YDuXviz2z+BXtvIgUIYOIVGp522O k5E3Jh8m6cP5yM5z9gL5LeEETuFNCbIOpO1pazrSxYGGg3X3gp6l6xbtgN/kAIWiliGL ekqMMMU5ZTFeUu+rxeggEd9OWWyhcFpF1qMzie5ZiFceH5oT5EU1EIcAVY4BOjQKMAnA gpfg== X-Gm-Message-State: AOAM531Y/1XLpnPqasGj7cxeN57gA282gpFXFT1AJr+7eGWozbkcFpUX 73sQHyZbUhjpYuRpqRv3kic= X-Google-Smtp-Source: ABdhPJz6v3FuQLY/R/FqBGyR1r2uQhUl0i7qarzPr6/Ir5EdlkqZ2FxD8rc/YLfFPehCSv3r3TvJnw== X-Received: by 2002:a17:902:aa86:b029:116:3e3a:2051 with SMTP id d6-20020a170902aa86b02901163e3a2051mr4076009plr.38.1626193753280; Tue, 13 Jul 2021 09:29:13 -0700 (PDT) Received: from localhost.localdomain ([118.200.190.93]) by smtp.gmail.com with ESMTPSA id oj4sm2979413pjb.56.2021.07.13.09.29.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Jul 2021 09:29:12 -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, 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 v2] Bluetooth: fix inconsistent lock state in sco Date: Wed, 14 Jul 2021 00:28:38 +0800 Message-Id: <20210713162838.693266-1-desmondcheongzx@gmail.com> X-Mailer: git-send-email 2.25.1 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 *** As sco_conn_del now disables local bh before calling sco_chan_del, instead of disabling local bh for the calls to sco_conn_lock in sco_chan_del, we instead wrap other calls to sco_chan_del with local_bh_disable/enable. Reported-by: syzbot+2f6d7c28bb4bf7e82060@syzkaller.appspotmail.com Tested-by: syzbot+2f6d7c28bb4bf7e82060@syzkaller.appspotmail.com Signed-off-by: Desmond Cheong Zhi Xi --- Hi, The previous version of this patch was a bit of a mess, so I made the following changes. v1 -> v2: - Instead of pulling out the clean-up code out from sco_chan_del and using it directly in sco_conn_del, disable local irqs for relevant sections. - Disable local irqs more thoroughly for instances of bh_lock_sock/bh_lock_sock_nested in the bluetooth subsystem. Specifically, the calls in af_bluetooth.c and rfcomm/sock.c are now made with local irqs disabled as well. Best wishes, Desmond net/bluetooth/rfcomm/sock.c | 2 ++ net/bluetooth/sco.c | 26 +++++++++++++++++++++++++- 2 files changed, 27 insertions(+), 1 deletion(-) diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c index ae6f80730561..d8734abb2df4 100644 --- a/net/bluetooth/rfcomm/sock.c +++ b/net/bluetooth/rfcomm/sock.c @@ -974,6 +974,7 @@ int rfcomm_connect_ind(struct rfcomm_session *s, u8 channel, struct rfcomm_dlc * if (!parent) return 0; + local_bh_disable(); bh_lock_sock(parent); /* Check for backlog size */ @@ -1002,6 +1003,7 @@ int rfcomm_connect_ind(struct rfcomm_session *s, u8 channel, struct rfcomm_dlc * done: bh_unlock_sock(parent); + local_bh_enable(); if (test_bit(BT_SK_DEFER_SETUP, &bt_sk(parent)->flags)) parent->sk_state_change(parent); diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c index 3bd41563f118..2548b8f81473 100644 --- a/net/bluetooth/sco.c +++ b/net/bluetooth/sco.c @@ -167,16 +167,22 @@ 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 +208,7 @@ 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 +216,7 @@ 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 +311,11 @@ 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; @@ -420,18 +430,25 @@ 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); - } else + local_bh_enable(); + } else { + local_bh_disable(); sco_chan_del(sk, ECONNRESET); + local_bh_enable(); + } break; case BT_CONNECT2: case BT_CONNECT: case BT_DISCONN: + local_bh_disable(); sco_chan_del(sk, ECONNRESET); + local_bh_enable(); break; default: @@ -1084,21 +1101,26 @@ 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 +1131,7 @@ 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 +1154,7 @@ static void sco_conn_ready(struct sco_conn *conn) bh_unlock_sock(parent); sco_conn_unlock(conn); + local_bh_enable(); } }