From patchwork Sun Jun 27 13:11:34 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tetsuo Handa X-Patchwork-Id: 12346803 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=-16.8 required=3.0 tests=BAYES_00, 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 5FDFDC48BC2 for ; Sun, 27 Jun 2021 13:12:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 29484619C5 for ; Sun, 27 Jun 2021 13:12:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230236AbhF0NOn (ORCPT ); Sun, 27 Jun 2021 09:14:43 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:57553 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229817AbhF0NOm (ORCPT ); Sun, 27 Jun 2021 09:14:42 -0400 Received: from fsav115.sakura.ne.jp (fsav115.sakura.ne.jp [27.133.134.242]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 15RDBh50091179; Sun, 27 Jun 2021 22:11:43 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav115.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav115.sakura.ne.jp); Sun, 27 Jun 2021 22:11:43 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav115.sakura.ne.jp) Received: from localhost.localdomain (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 15RDBcTs091155 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Sun, 27 Jun 2021 22:11:43 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) From: Tetsuo Handa To: Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org Cc: "David S. Miller" , Jakub Kicinski , Lin Ma , netdev@vger.kernel.org, Tetsuo Handa Subject: [PATCH] Bluetooth: call lock_sock() outside of spinlock section Date: Sun, 27 Jun 2021 22:11:34 +0900 Message-Id: <20210627131134.5434-1-penguin-kernel@I-love.SAKURA.ne.jp> X-Mailer: git-send-email 2.18.4 Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org syzbot is hitting might_sleep() warning at hci_sock_dev_event() due to calling lock_sock() with rw spinlock held [1]. Defer calling lock_sock() via sock_hold(). Link: https://syzkaller.appspot.com/bug?extid=a5df189917e79d5e59c9 [1] Reported-by: syzbot Signed-off-by: Tetsuo Handa Tested-by: syzbot Fixes: e305509e678b3a4a ("Bluetooth: use correct lock to prevent UAF of hdev object") --- net/bluetooth/hci_sock.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c index eed0dd066e12..64e54ab0892f 100644 --- a/net/bluetooth/hci_sock.c +++ b/net/bluetooth/hci_sock.c @@ -759,19 +759,39 @@ void hci_sock_dev_event(struct hci_dev *hdev, int event) if (event == HCI_DEV_UNREG) { struct sock *sk; +restart: /* Detach sockets from device */ read_lock(&hci_sk_list.lock); sk_for_each(sk, &hci_sk_list.head) { + /* hci_sk_list.lock is preventing hci_sock_release() + * from calling bt_sock_unlink(). + */ + if (hci_pi(sk)->hdev != hdev || sk_unhashed(sk)) + continue; + /* Take a ref because we can't call lock_sock() with + * hci_sk_list.lock held. + */ + sock_hold(sk); + read_unlock(&hci_sk_list.lock); lock_sock(sk); - if (hci_pi(sk)->hdev == hdev) { + /* Since hci_sock_release() might have already called + * bt_sock_unlink() while waiting for lock_sock(), + * use sk_hashed(sk) for checking that bt_sock_unlink() + * is not yet called. + */ + if (sk_hashed(sk) && hci_pi(sk)->hdev == hdev) { hci_pi(sk)->hdev = NULL; sk->sk_err = EPIPE; sk->sk_state = BT_OPEN; sk->sk_state_change(sk); - hci_dev_put(hdev); } release_sock(sk); + sock_put(sk); + /* Restarting is safe, for hci_pi(sk)->hdev is now NULL + * if condition met and will "continue;" otherwise. + */ + goto restart; } read_unlock(&hci_sk_list.lock); }