From patchwork Wed Oct 18 10:30:55 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bastien Nocera X-Patchwork-Id: 737401 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6599CDB483 for ; Wed, 18 Oct 2023 10:32:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230462AbjJRKcz (ORCPT ); Wed, 18 Oct 2023 06:32:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34094 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229844AbjJRKcy (ORCPT ); Wed, 18 Oct 2023 06:32:54 -0400 Received: from relay6-d.mail.gandi.net (relay6-d.mail.gandi.net [IPv6:2001:4b98:dc4:8::226]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2E74CEA for ; Wed, 18 Oct 2023 03:32:50 -0700 (PDT) Received: by mail.gandi.net (Postfix) with ESMTPSA id E802CC0007; Wed, 18 Oct 2023 10:32:48 +0000 (UTC) From: Bastien Nocera To: linux-bluetooth@vger.kernel.org Cc: ZhengHan Wang , Luiz Augusto von Dentz Subject: [PATCH v3] Bluetooth: Fix double free in hci_conn_cleanup Date: Wed, 18 Oct 2023 12:30:55 +0200 Message-ID: <20231018103248.294565-1-hadess@hadess.net> X-Mailer: git-send-email 2.41.0 MIME-Version: 1.0 X-GND-Sasl: hadess@hadess.net Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org From: ZhengHan Wang syzbot reports a slab use-after-free in hci_conn_hash_flush [1]. After releasing an object using hci_conn_del_sysfs in the hci_conn_cleanup function, releasing the same object again using the hci_dev_put and hci_conn_put functions causes a double free. Here's a simplified flow: hci_conn_del_sysfs: hci_dev_put put_device kobject_put kref_put kobject_release kobject_cleanup kfree_const kfree(name) hci_dev_put: ... kfree(name) hci_conn_put: put_device ... kfree(name) This patch drop the hci_dev_put and hci_conn_put function call in hci_conn_cleanup function, because the object is freed in hci_conn_del_sysfs function. This patch also fixes the refcounting in hci_conn_add_sysfs() and hci_conn_del_sysfs() to take into account device_add() failures. This fixes CVE-2023-28464. Link: https://syzkaller.appspot.com/bug?id=1bb51491ca5df96a5f724899d1dbb87afda61419 [1] Signed-off-by: ZhengHan Wang Co-developed-by: Luiz Augusto von Dentz --- Re-sending Luiz' version of ZhengHan Wang's patch as a reply-to snafu caused v2 of the patch by Luiz to not be applied. I added the CVE reference, fixed the SoB and add mention of Luiz' changes in the commit message. net/bluetooth/hci_conn.c | 6 ++---- net/bluetooth/hci_sysfs.c | 23 ++++++++++++----------- 2 files changed, 14 insertions(+), 15 deletions(-) diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c index 7a6f20338db8..236085451931 100644 --- a/net/bluetooth/hci_conn.c +++ b/net/bluetooth/hci_conn.c @@ -169,13 +169,11 @@ static void hci_conn_cleanup(struct hci_conn *conn) hdev->notify(hdev, HCI_NOTIFY_CONN_DEL); } - hci_conn_del_sysfs(conn); - debugfs_remove_recursive(conn->debugfs); - hci_dev_put(hdev); + hci_conn_del_sysfs(conn); - hci_conn_put(conn); + hci_dev_put(hdev); } static void hci_acl_create_connection(struct hci_conn *conn) diff --git a/net/bluetooth/hci_sysfs.c b/net/bluetooth/hci_sysfs.c index 15b33579007c..367e32fe30eb 100644 --- a/net/bluetooth/hci_sysfs.c +++ b/net/bluetooth/hci_sysfs.c @@ -35,7 +35,7 @@ void hci_conn_init_sysfs(struct hci_conn *conn) { struct hci_dev *hdev = conn->hdev; - BT_DBG("conn %p", conn); + bt_dev_dbg(hdev, "conn %p", conn); conn->dev.type = &bt_link; conn->dev.class = &bt_class; @@ -48,27 +48,30 @@ void hci_conn_add_sysfs(struct hci_conn *conn) { struct hci_dev *hdev = conn->hdev; - BT_DBG("conn %p", conn); + bt_dev_dbg(hdev, "conn %p", conn); if (device_is_registered(&conn->dev)) return; dev_set_name(&conn->dev, "%s:%d", hdev->name, conn->handle); - if (device_add(&conn->dev) < 0) { + if (device_add(&conn->dev) < 0) bt_dev_err(hdev, "failed to register connection device"); - return; - } - - hci_dev_hold(hdev); } void hci_conn_del_sysfs(struct hci_conn *conn) { struct hci_dev *hdev = conn->hdev; - if (!device_is_registered(&conn->dev)) + bt_dev_dbg(hdev, "conn %p", conn); + + if (!device_is_registered(&conn->dev)) { + /* If device_add() has *not* succeeded, use *only* put_device() + * to drop the reference count. + */ + put_device(&conn->dev); return; + } while (1) { struct device *dev; @@ -80,9 +83,7 @@ void hci_conn_del_sysfs(struct hci_conn *conn) put_device(dev); } - device_del(&conn->dev); - - hci_dev_put(hdev); + device_unregister(&conn->dev); } static void bt_host_release(struct device *dev)