From mboxrd@z Thu Jan 1 00:00:00 1970 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 15D90C4332F for ; Tue, 10 May 2022 13:16:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242576AbiEJNUh (ORCPT ); Tue, 10 May 2022 09:20:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37730 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242388AbiEJNSK (ORCPT ); Tue, 10 May 2022 09:18:10 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 83E173DDD9; Tue, 10 May 2022 06:13:00 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id B50E4615DD; Tue, 10 May 2022 13:12:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C4934C385A6; Tue, 10 May 2022 13:12:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1652188379; bh=PLBcffHUTxEwDYZ2I2HzXLMI033QZq0mU5i+o1QVl8o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0a5qaPLu313ocHSrV6Duz7JF+ib+kGAo6CtCN9L1I8fFcOLA4MEAkH9XeDE8ogrQO AH+fVPhm/mDSCwgoy04UcayRbKR01pPSSC8npMYJi6ycivxo57itf4Fjn0EtX0e5o9 wkViNI7XHQW7Hh05RYLs0dTjZaOppcmWRhXU7eYE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Duoming Zhou , "David S. Miller" Subject: [PATCH 4.9 53/66] nfc: replace improper check device_is_registered() in netlink related functions Date: Tue, 10 May 2022 15:07:43 +0200 Message-Id: <20220510130731.321915579@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220510130729.762341544@linuxfoundation.org> References: <20220510130729.762341544@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: Duoming Zhou commit da5c0f119203ad9728920456a0f52a6d850c01cd upstream. The device_is_registered() in nfc core is used to check whether nfc device is registered in netlink related functions such as nfc_fw_download(), nfc_dev_up() and so on. Although device_is_registered() is protected by device_lock, there is still a race condition between device_del() and device_is_registered(). The root cause is that kobject_del() in device_del() is not protected by device_lock. (cleanup task) | (netlink task) | nfc_unregister_device | nfc_fw_download device_del | device_lock ... | if (!device_is_registered)//(1) kobject_del//(2) | ... ... | device_unlock The device_is_registered() returns the value of state_in_sysfs and the state_in_sysfs is set to zero in kobject_del(). If we pass check in position (1), then set zero in position (2). As a result, the check in position (1) is useless. This patch uses bool variable instead of device_is_registered() to judge whether the nfc device is registered, which is well synchronized. Fixes: 3e256b8f8dfa ("NFC: add nfc subsystem core") Signed-off-by: Duoming Zhou Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/nfc/core.c | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-) --- a/net/nfc/core.c +++ b/net/nfc/core.c @@ -50,7 +50,7 @@ int nfc_fw_download(struct nfc_dev *dev, device_lock(&dev->dev); - if (!device_is_registered(&dev->dev)) { + if (dev->shutting_down) { rc = -ENODEV; goto error; } @@ -106,7 +106,7 @@ int nfc_dev_up(struct nfc_dev *dev) device_lock(&dev->dev); - if (!device_is_registered(&dev->dev)) { + if (dev->shutting_down) { rc = -ENODEV; goto error; } @@ -154,7 +154,7 @@ int nfc_dev_down(struct nfc_dev *dev) device_lock(&dev->dev); - if (!device_is_registered(&dev->dev)) { + if (dev->shutting_down) { rc = -ENODEV; goto error; } @@ -218,7 +218,7 @@ int nfc_start_poll(struct nfc_dev *dev, device_lock(&dev->dev); - if (!device_is_registered(&dev->dev)) { + if (dev->shutting_down) { rc = -ENODEV; goto error; } @@ -257,7 +257,7 @@ int nfc_stop_poll(struct nfc_dev *dev) device_lock(&dev->dev); - if (!device_is_registered(&dev->dev)) { + if (dev->shutting_down) { rc = -ENODEV; goto error; } @@ -302,7 +302,7 @@ int nfc_dep_link_up(struct nfc_dev *dev, device_lock(&dev->dev); - if (!device_is_registered(&dev->dev)) { + if (dev->shutting_down) { rc = -ENODEV; goto error; } @@ -346,7 +346,7 @@ int nfc_dep_link_down(struct nfc_dev *de device_lock(&dev->dev); - if (!device_is_registered(&dev->dev)) { + if (dev->shutting_down) { rc = -ENODEV; goto error; } @@ -412,7 +412,7 @@ int nfc_activate_target(struct nfc_dev * device_lock(&dev->dev); - if (!device_is_registered(&dev->dev)) { + if (dev->shutting_down) { rc = -ENODEV; goto error; } @@ -458,7 +458,7 @@ int nfc_deactivate_target(struct nfc_dev device_lock(&dev->dev); - if (!device_is_registered(&dev->dev)) { + if (dev->shutting_down) { rc = -ENODEV; goto error; } @@ -505,7 +505,7 @@ int nfc_data_exchange(struct nfc_dev *de device_lock(&dev->dev); - if (!device_is_registered(&dev->dev)) { + if (dev->shutting_down) { rc = -ENODEV; kfree_skb(skb); goto error; @@ -562,7 +562,7 @@ int nfc_enable_se(struct nfc_dev *dev, u device_lock(&dev->dev); - if (!device_is_registered(&dev->dev)) { + if (dev->shutting_down) { rc = -ENODEV; goto error; } @@ -611,7 +611,7 @@ int nfc_disable_se(struct nfc_dev *dev, device_lock(&dev->dev); - if (!device_is_registered(&dev->dev)) { + if (dev->shutting_down) { rc = -ENODEV; goto error; } @@ -1142,6 +1142,7 @@ int nfc_register_device(struct nfc_dev * dev->rfkill = NULL; } } + dev->shutting_down = false; device_unlock(&dev->dev); rc = nfc_genl_device_added(dev); @@ -1174,12 +1175,10 @@ void nfc_unregister_device(struct nfc_de rfkill_unregister(dev->rfkill); rfkill_destroy(dev->rfkill); } + dev->shutting_down = true; device_unlock(&dev->dev); if (dev->ops->check_presence) { - device_lock(&dev->dev); - dev->shutting_down = true; - device_unlock(&dev->dev); del_timer_sync(&dev->check_pres_timer); cancel_work_sync(&dev->check_pres_work); }