From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A8CD72DF92 for ; Tue, 7 Nov 2023 12:08:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="IaBSzQMq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 59A78C433CC; Tue, 7 Nov 2023 12:08:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699358906; bh=JaI066b+mCXWtqSok9hBW4AJ9FeTe0b469OtgVh/uT8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IaBSzQMq/TmTV6t0sG/AxA/lmo+vs4Na+NmKPWN1WtM/fMpWjDlifun1gjIEYeSEP JHMsnfx235uwUeHlyLRnFf0hx1paPATidq22H9YeQVBtE/XnT+QatEpFV6/U0kFxQI 3ztHAFumkzJVAe/gHFsZwcUjp6p0Vl6SwNHDLkSTyjRbHu8YcmAhZTj1Jij3xrWHXW xa5nh/IaPBvG66F+08rBqS44HVKF0VlAzIC4WDkdMYP5vNFCuA9g5duajDEsErtbgh QZFvQpIc8jPYPmEId2nTn5bDF/UUMfZVrZr6ralcCisQfWnhp3mwSKg0v+Cbvgkhs/ AaVDFa57pBZ8A== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: ZhengHan Wang , Luiz Augusto von Dentz , Sasha Levin , marcel@holtmann.org, johan.hedberg@gmail.com, luiz.dentz@gmail.com, linux-bluetooth@vger.kernel.org Subject: [PATCH AUTOSEL 6.6 25/31] Bluetooth: Fix double free in hci_conn_cleanup Date: Tue, 7 Nov 2023 07:06:12 -0500 Message-ID: <20231107120704.3756327-25-sashal@kernel.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231107120704.3756327-1-sashal@kernel.org> References: <20231107120704.3756327-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-bluetooth@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.6 Content-Transfer-Encoding: 8bit From: ZhengHan Wang [ Upstream commit a85fb91e3d728bdfc80833167e8162cce8bc7004 ] 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 Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Sasha Levin --- 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 73470cc3518a7..7dd6a4fe25c1b 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 15b33579007cb..367e32fe30eb8 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) -- 2.42.0