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 EC868C433F5 for ; Tue, 10 May 2022 13:50:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244332AbiEJNys (ORCPT ); Tue, 10 May 2022 09:54:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53198 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244015AbiEJNwx (ORCPT ); Tue, 10 May 2022 09:52:53 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BC7AF6B7CF; Tue, 10 May 2022 06:38:15 -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 ams.source.kernel.org (Postfix) with ESMTPS id 8FAC3B81DB1; Tue, 10 May 2022 13:37:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 03BAFC385C6; Tue, 10 May 2022 13:37:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1652189851; bh=r/8WhCII/QSwBbGHS0M4iDqpyet3/YT26qUmf2G5itc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HUbW0eiEStVIR82gHucTw8KMJnJlUr4dFDqlIVx1/+DNwvz/c2K0jBDU5zPBxtSTK 6vgl15xPp+xgap0Jd4rZXN4Iplb/anvx+vTINItnFBEwaige+bjtubosC8UPW0xbez yNyLznP39gRr1CyPFMD2t3WS7JYeMTI9GUZtBNrY= 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 5.17 050/140] nfc: replace improper check device_is_registered() in netlink related functions Date: Tue, 10 May 2022 15:07:20 +0200 Message-Id: <20220510130743.050488097@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220510130741.600270947@linuxfoundation.org> References: <20220510130741.600270947@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: stable@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 @@ -38,7 +38,7 @@ 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; } @@ -94,7 +94,7 @@ 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; } @@ -142,7 +142,7 @@ 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; } @@ -207,7 +207,7 @@ 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; } @@ -246,7 +246,7 @@ 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; } @@ -291,7 +291,7 @@ 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; } @@ -335,7 +335,7 @@ 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; } @@ -401,7 +401,7 @@ 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; } @@ -448,7 +448,7 @@ 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; } @@ -495,7 +495,7 @@ 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; @@ -552,7 +552,7 @@ 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; } @@ -601,7 +601,7 @@ 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; } @@ -1134,6 +1134,7 @@ int nfc_register_device(struct nfc_dev * dev->rfkill = NULL; } } + dev->shutting_down = false; device_unlock(&dev->dev); rc = nfc_genl_device_added(dev); @@ -1166,12 +1167,10 @@ 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); }