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To: Alexei Starovoitov , CC: , , , , References: <20201014175608.1416-1-alexei.starovoitov@gmail.com> From: Yonghong Song Message-ID: <4ec07471-5d8c-5aba-1f0e-65fe61c4d298@fb.com> Date: Wed, 14 Oct 2020 22:46:47 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 In-Reply-To: <20201014175608.1416-1-alexei.starovoitov@gmail.com> Content-Language: en-US X-Originating-IP: [2620:10d:c091:480::1:2a8a] X-ClientProxiedBy: MN2PR15CA0037.namprd15.prod.outlook.com (2603:10b6:208:237::6) To BYAPR15MB4088.namprd15.prod.outlook.com (2603:10b6:a02:c3::18) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [IPv6:2620:10d:c0a8:11c9::138b] (2620:10d:c091:480::1:2a8a) by MN2PR15CA0037.namprd15.prod.outlook.com (2603:10b6:208:237::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3477.21 via Frontend Transport; Thu, 15 Oct 2020 05:46:50 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 4a1cc8e2-6577-4353-e33d-08d870cdb78d X-MS-TrafficTypeDiagnostic: BY5PR15MB3571: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-FB-Source: Internal X-MS-Oob-TLC-OOBClassifiers: OLM:6430; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: v6wm0vrN4MuqOA6VWCV2YOcE5N/wnEtBr/pbcpSIK3Ih7FWhEOpBAHyjloz2IUssSizigzVviqS7sDNewFP4K1yD8oTBubbliKEGq/cuzmmRjKBZdZ+Cv+tXltTJZKoL99Vw/1mtVXrwGRDhg2fvlGbJ2HrWHtxqwrOGQ7s8a+Vf4Zq6S2j8hZ2HPrxjTYR2TAU4fSwIF2fKStKLGnBB29PbWiJuzje46vwxaY2ofUPoSRtjsIaXKkFyAIaLlnYUgdfooSOpFVGjTcau/xW2KbvjGmkMXO05IuG6ZyCH9CzJtRbZ8NQsJ0dJVyMvA0b2sT6oAJxqOuY2mdvingN9I4lrG/qGt4hvYCnKL9Sa267bqhq8Al0MI+KRlJJZ7E9z X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BYAPR15MB4088.namprd15.prod.outlook.com;PTR:;CAT:NONE;SFS:(346002)(136003)(366004)(376002)(396003)(39860400002)(6666004)(186003)(86362001)(16526019)(6486002)(53546011)(36756003)(316002)(2906002)(4326008)(31696002)(8936002)(478600001)(66946007)(8676002)(5660300002)(52116002)(31686004)(66556008)(2616005)(66476007)(43740500002);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData: 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 X-MS-Exchange-CrossTenant-Network-Message-Id: 4a1cc8e2-6577-4353-e33d-08d870cdb78d X-MS-Exchange-CrossTenant-AuthSource: BYAPR15MB4088.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Oct 2020 05:46:52.6249 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 5Ot6PtnYFR7EXbxUC9bpRl6CeCAcXB1yll7LqZeTZN4MAqqK7x89Yolz8BpsovPg X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR15MB3571 X-OriginatorOrg: fb.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-10-15_03:2020-10-14,2020-10-15 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 malwarescore=0 clxscore=1015 suspectscore=0 adultscore=0 bulkscore=0 spamscore=0 priorityscore=1501 impostorscore=0 lowpriorityscore=0 phishscore=0 mlxscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2010150041 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 10/14/20 10:56 AM, Alexei Starovoitov wrote: > From: Alexei Starovoitov > > The 64-bit JEQ/JNE handling in reg_set_min_max() was clearing reg->id in either > true or false branch. In the case 'if (reg->id)' check was done on the other > branch the counter part register would have reg->id == 0 when called into > find_equal_scalars(). In such case the helper would incorrectly identify other > registers with id == 0 as equivalent and propagate the state incorrectly. > Fix it by preserving ID across reg_set_min_max(). > In other words any kind of comparison operator on the scalar register > should preserve its ID to recognize: > r1 = r2 > if (r1 == 20) { > #1 here both r1 and r2 == 20 > } else if (r2 < 20) { > #2 here both r1 and r2 < 20 > } > > The patch is addressing #1 case. The #2 was working correctly already. > > Fixes: 75748837b7e5 ("bpf: Propagate scalar ranges through register assignments.") > Signed-off-by: Alexei Starovoitov This fixed an issue appeared in our production system where packets may be incorrectly dropped. Test-by: Yonghong Song