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Thu, 30 Sep 2021 09:04:21 +0000 Received: from DB7PR04MB5050.eurprd04.prod.outlook.com ([fe80::61c5:2592:9e7f:a390]) by DB7PR04MB5050.eurprd04.prod.outlook.com ([fe80::61c5:2592:9e7f:a390%5]) with mapi id 15.20.4566.014; Thu, 30 Sep 2021 09:04:21 +0000 Subject: Re: [PATCH 1/2] USB: cdc-acm: fix racy tty buffer accesses To: Johan Hovold , Oliver Neukum , Greg Kroah-Hartman Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20210929090937.7410-1-johan@kernel.org> <20210929090937.7410-2-johan@kernel.org> From: Oliver Neukum Message-ID: Date: Thu, 30 Sep 2021 11:04:19 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 In-Reply-To: <20210929090937.7410-2-johan@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-ClientProxiedBy: AM6PR02CA0014.eurprd02.prod.outlook.com (2603:10a6:20b:6e::27) To DB7PR04MB5050.eurprd04.prod.outlook.com (2603:10a6:10:22::23) MIME-Version: 1.0 Received: from linux.fritz.box (2001:a61:3b0d:4601:21ab:d1da:15e9:ca07) by AM6PR02CA0014.eurprd02.prod.outlook.com (2603:10a6:20b:6e::27) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4566.14 via Frontend Transport; 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For example, in case a host-controller driver uses > bottom-half completion, the interrupt and bulk-in completion handlers > can end up running in parallel on two CPUs (high-and low-prio tasklets, > respectively) thereby breaking the tty layer's single producer > assumption. > > Fix this by holding the read lock also when inserting characters from > the bulk endpoint. > > Fixes: 08dff274edda ("cdc-acm: fix BREAK rx code path adding necessary calls") > Cc: stable@vger.kernel.org > Signed-off-by: Johan Hovold Acked-by: Oliver Neukum