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Mon, 14 Feb 2022 19:30:05 +0000 Received: from DB7PR04MB5050.eurprd04.prod.outlook.com ([fe80::98e0:cb7:30fd:254f]) by DB7PR04MB5050.eurprd04.prod.outlook.com ([fe80::98e0:cb7:30fd:254f%5]) with mapi id 15.20.4975.018; Mon, 14 Feb 2022 19:30:05 +0000 Message-ID: <393ec81c-52b4-842b-1ecd-4ffc29743665@suse.com> Date: Mon, 14 Feb 2022 20:30:02 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [RFC] CDC-NCM: avoid overflow in sanity checking Content-Language: en-US To: =?UTF-8?Q?Bj=c3=b8rn_Mork?= , Alan Stern CC: Hans Petter Selasky , Oliver Neukum , linux-usb@vger.kernel.org, netdev@vger.kernel.org References: <20220210155455.4601-1-oneukum@suse.com> <87v8xmocng.fsf@miraculix.mork.no> <3624a7e7-3568-bee1-77e5-67d5b7d48aa6@selasky.org> <87k0e1oory.fsf@miraculix.mork.no> From: Oliver Neukum In-Reply-To: <87k0e1oory.fsf@miraculix.mork.no> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: AM6PR10CA0029.EURPRD10.PROD.OUTLOOK.COM (2603:10a6:209:89::42) To DB7PR04MB5050.eurprd04.prod.outlook.com (2603:10a6:10:22::23) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 9a4964dd-dd95-4838-1866-08d9eff06719 X-MS-TrafficTypeDiagnostic: AM6PR04MB4325:EE_ X-LD-Processed: f7a17af6-1c5c-4a36-aa8b-f5be247aa4ba,ExtFwd X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:6108; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?sAASz81deDLwVOOO3eRbfP2Zr5fz/YacsrqbASGQPo8uNTYFKkuSb5NZY4qb?= =?us-ascii?Q?TlGqeDUBPxpB/hklmfFJvIkLxRzKxsN+C5zioMPQVsRjBoyMsmYE+OncQAL0?= =?us-ascii?Q?cwPZmQ2lOhZIvz2P8bpaPaqKvEiVgXf1Tg2qcRnElnBHhxotc7Pt/ypL9lFg?= =?us-ascii?Q?PlDhHxemc2OgpLzdYCwXXWPADGbu7rO19eauHwbXQIXKldO0wSvx5X8f6fag?= =?us-ascii?Q?7L02MzUHPPkOXfGHoIzSonq0S6PxioKeDmWYB5p+Tfy3gofaYBrRHkZpaNog?= =?us-ascii?Q?J5FSVSrqcEVTJ32mlD2g2Tlzl6n5UcHWfkj8FUqrsoWbmTMNIBg17D+wc+8e?= =?us-ascii?Q?z4XSwkCax492uwJcbBTCayW+PcFefngab6CW75IAUruv0St7nJADfIH/FBtf?= =?us-ascii?Q?osOg3JpJ5HkKBdlcxMAKaqaIySR+b3VmYJMO0dxvtcGjqejrKzvAEWNnvl7Q?= =?us-ascii?Q?AkHJzN12yLSQuRrCydKQ436SxsrTI8nbXW812QjAkxo1jbqcZEauyROnbY2R?= =?us-ascii?Q?5GNh1m710dgEhAVFhnixGRG9E6E82bwkYwt0GgjVyFvaZlhpljT5PHhlEmXn?= =?us-ascii?Q?sHTwBKXkwvFOgDhLJZJbzT8DOXFqotaJk0vsF3cKVFVk6le/2JSaC5ZvX4LN?= =?us-ascii?Q?n9lm7LriAw1LZivdRbwOn5hs5pxiKpXzDJhiPZX1X4jqWm+FCyQctUqbZ5Np?= =?us-ascii?Q?3Qwag4mlWTeG60YxJiUjY0LSF1qq6nK9doNgaEgNPWtQe3h0R4O+w9O7A7P/?= =?us-ascii?Q?sq4oFJtuC2bGmtwfX48Wy3/mSs3OhioJeDH+yljuf3iMQoh4kx2VOxm5R4/n?= =?us-ascii?Q?d1OfQSo5SKU0IBXYVXGeZ9nT5Lhd0n82gLMyv9B49G7Cq1HekAatST5etsZn?= =?us-ascii?Q?xBV3211eMfmcBOYt2dXH9QFtdFNEYo5V6umPtaOEDz6Hvk+0c+0DpMBR35Ti?= =?us-ascii?Q?yIfwEHLpVNobZw4YTVO6qdot73X27KW6CLySwqq+fPpd8as3quZD3Kn+uQhF?= =?us-ascii?Q?t6+Ad3jv2KbA/G5zP+ihZHOLu+oyyTxKTPMrOI0y2cCcSnfcFodBCqno7ISr?= =?us-ascii?Q?/a64jEAtRa5jO04oNm48cpu1j8+juWI8F84A5QLPO8dzBYsI1NzQHg7DAY+u?= =?us-ascii?Q?BNHBz3yPnvRSi4/kWJ9PIbvunoG/x3Eb92mhUffDadI56iSTQQ4mZoZiPmZR?= =?us-ascii?Q?Bmblc1tkhOoPkMTdj6WmIskMf3mminh2h+PClwZZZXLni2EfFIYImpGExLzh?= =?us-ascii?Q?6b770krw03qnD349+EAlSAn6JENzX0BTSwfPA0zMMWGcn31D704je8GjvIci?= =?us-ascii?Q?Hk6SzDsb9Ee8uHJWEaJ/cwn1PCpLm1l1SQBcCyHH7pW+48IeyMQmHexlzilf?= =?us-ascii?Q?sugy7T5s2OabCCQ0Oit6jAMWZ2ceYBSjo7EAEPiLinNsWJkIg5/+zW9O2Hvn?= =?us-ascii?Q?FNPKDO/C3JIlPAJi4oRgEI64pkus+Xf3OdN2RVgLgAu3/zGnOD0cCZYi+WWA?= =?us-ascii?Q?SaWURMS3XLi1YaOgOiWZKMNY287JFj5E/vqiuaXHx9bfnAqd5+OLjjOjVsdP?= =?us-ascii?Q?M/4gx5zHvpvYiRnGh6+QhnG1URLnDK3g3HvxEhiD71iIlNCCOpbbR2vjtSeO?= =?us-ascii?Q?oiq2N/NiFFF3wCSdmd07hXLI+gRtaV+7OpuPFDaMI/OZeqjJ1Ef8ouKFvDQv?= =?us-ascii?Q?3piSScPsUl+7+0JPB/Q1aLZMtzQ=3D?= X-OriginatorOrg: suse.com X-MS-Exchange-CrossTenant-Network-Message-Id: 9a4964dd-dd95-4838-1866-08d9eff06719 X-MS-Exchange-CrossTenant-AuthSource: DB7PR04MB5050.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Feb 2022 19:30:05.3960 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: f7a17af6-1c5c-4a36-aa8b-f5be247aa4ba X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: LLqqA6h4YROthIofdjnuxvXe2bur8NQpNFMkxsE/CqaqSL822YikXmXVjUwXTkq8bOZAgE4BOb5RpCzJeP5s0Q== X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM6PR04MB4325 Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On 11.02.22 08:17, Bj=C3=B8rn Mork wrote: > Alan Stern writes: > > > Only is that the existing code wants the inverted result: > > if (offset > skb_in->len || len > skb_in->len - offset) ... > > with all values unsigned. Its logic is if (!sane(fragment)) =C2=A0=C2=A0=C2=A0 continue; process(fragment); rather than if (sane(fragment)) =C2=A0=C2=A0=C2=A0 process(fragment); A simple matter of inversion. > And there you point out my problem: discipline :-) > Do we still agree that unsigned integers are the better option? =C2=A0=C2=A0=C2=A0 Regards =C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 Oliver