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 3437EC433F5 for ; Wed, 24 Nov 2021 13:56:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353324AbhKXN7y (ORCPT ); Wed, 24 Nov 2021 08:59:54 -0500 Received: from mail.kernel.org ([198.145.29.99]:46988 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353069AbhKXN4n (ORCPT ); Wed, 24 Nov 2021 08:56:43 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 329A363370; Wed, 24 Nov 2021 13:06:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1637759212; bh=xEFqqXiRcaFt4gLdA1oq4qnjLxzPR09VjFrD+w7FhaQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hYZbv3E92JZiP6BAUs67/j4jIWLxxR+devZZc444W1vFxoKhdQiI7JAwdi4MaAfos EVBGk1oXYIUQC9fLpPkf8oCF0MxIyKkNVwHbjqDfcQi/UHy63qKNT9L9NSSlvK3G9e 8ZWdzUjXigE2IO/9QkYMxhbnQ7Os74cb/D3u4gsI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lin Ma , Jakub Kicinski , Krzysztof Kozlowski , Sasha Levin Subject: [PATCH 5.15 169/279] NFC: reorder the logic in nfc_{un,}register_device Date: Wed, 24 Nov 2021 12:57:36 +0100 Message-Id: <20211124115724.582691224@linuxfoundation.org> X-Mailer: git-send-email 2.34.0 In-Reply-To: <20211124115718.776172708@linuxfoundation.org> References: <20211124115718.776172708@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lin Ma [ Upstream commit 3e3b5dfcd16a3e254aab61bd1e8c417dd4503102 ] There is a potential UAF between the unregistration routine and the NFC netlink operations. The race that cause that UAF can be shown as below: (FREE) | (USE) nfcmrvl_nci_unregister_dev | nfc_genl_dev_up nci_close_device | nci_unregister_device | nfc_get_device nfc_unregister_device | nfc_dev_up rfkill_destory | device_del | rfkill_blocked ... | ... The root cause for this race is concluded below: 1. The rfkill_blocked (USE) in nfc_dev_up is supposed to be placed after the device_is_registered check. 2. Since the netlink operations are possible just after the device_add in nfc_register_device, the nfc_dev_up() can happen anywhere during the rfkill creation process, which leads to data race. This patch reorder these actions to permit 1. Once device_del is finished, the nfc_dev_up cannot dereference the rfkill object. 2. The rfkill_register need to be placed after the device_add of nfc_dev because the parent device need to be created first. So this patch keeps the order but inject device_lock to prevent the data race. Signed-off-by: Lin Ma Fixes: be055b2f89b5 ("NFC: RFKILL support") Reviewed-by: Jakub Kicinski Reviewed-by: Krzysztof Kozlowski Link: https://lore.kernel.org/r/20211116152652.19217-1-linma@zju.edu.cn Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/nfc/core.c | 32 ++++++++++++++++++-------------- 1 file changed, 18 insertions(+), 14 deletions(-) diff --git a/net/nfc/core.c b/net/nfc/core.c index 3c645c1d99c9b..dc7a2404efdf9 100644 --- a/net/nfc/core.c +++ b/net/nfc/core.c @@ -94,13 +94,13 @@ int nfc_dev_up(struct nfc_dev *dev) device_lock(&dev->dev); - if (dev->rfkill && rfkill_blocked(dev->rfkill)) { - rc = -ERFKILL; + if (!device_is_registered(&dev->dev)) { + rc = -ENODEV; goto error; } - if (!device_is_registered(&dev->dev)) { - rc = -ENODEV; + if (dev->rfkill && rfkill_blocked(dev->rfkill)) { + rc = -ERFKILL; goto error; } @@ -1125,11 +1125,7 @@ int nfc_register_device(struct nfc_dev *dev) if (rc) pr_err("Could not register llcp device\n"); - rc = nfc_genl_device_added(dev); - if (rc) - pr_debug("The userspace won't be notified that the device %s was added\n", - dev_name(&dev->dev)); - + device_lock(&dev->dev); dev->rfkill = rfkill_alloc(dev_name(&dev->dev), &dev->dev, RFKILL_TYPE_NFC, &nfc_rfkill_ops, dev); if (dev->rfkill) { @@ -1138,6 +1134,12 @@ int nfc_register_device(struct nfc_dev *dev) dev->rfkill = NULL; } } + device_unlock(&dev->dev); + + rc = nfc_genl_device_added(dev); + if (rc) + pr_debug("The userspace won't be notified that the device %s was added\n", + dev_name(&dev->dev)); return 0; } @@ -1154,10 +1156,17 @@ void nfc_unregister_device(struct nfc_dev *dev) pr_debug("dev_name=%s\n", dev_name(&dev->dev)); + rc = nfc_genl_device_removed(dev); + if (rc) + pr_debug("The userspace won't be notified that the device %s " + "was removed\n", dev_name(&dev->dev)); + + device_lock(&dev->dev); if (dev->rfkill) { rfkill_unregister(dev->rfkill); rfkill_destroy(dev->rfkill); } + device_unlock(&dev->dev); if (dev->ops->check_presence) { device_lock(&dev->dev); @@ -1167,11 +1176,6 @@ void nfc_unregister_device(struct nfc_dev *dev) cancel_work_sync(&dev->check_pres_work); } - rc = nfc_genl_device_removed(dev); - if (rc) - pr_debug("The userspace won't be notified that the device %s " - "was removed\n", dev_name(&dev->dev)); - nfc_llcp_unregister_device(dev); mutex_lock(&nfc_devlist_mutex); -- 2.33.0