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Message-ID: <2f60e273-e8e3-848d-f3fd-68d7318e2e62@suse.com> Date: Thu, 9 Feb 2023 16:32:42 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 From: Jan Beulich Subject: [PATCH v2] x86/p2m: tighten old-MFN check in p2m_add_page() To: "xen-devel@lists.xenproject.org" Cc: Andrew Cooper , Wei Liu , =?utf-8?q?Roger_Pau_Monn=C3=A9?= , George Dunlap Content-Language: en-US X-ClientProxiedBy: FR0P281CA0119.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:a8::17) To VE1PR04MB6560.eurprd04.prod.outlook.com (2603:10a6:803:122::25) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: VE1PR04MB6560:EE_|AM9PR04MB8274:EE_ X-MS-Office365-Filtering-Correlation-Id: e3521cb0-c010-4e9a-a511-08db0ab2e393 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:VE1PR04MB6560.eurprd04.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230025)(136003)(366004)(376002)(346002)(39860400002)(396003)(451199018)(5660300002)(26005)(31696002)(86362001)(186003)(8936002)(2616005)(38100700002)(6512007)(83380400001)(54906003)(41300700001)(4326008)(66946007)(316002)(6916009)(66556008)(8676002)(66476007)(6506007)(478600001)(6486002)(36756003)(31686004)(2906002)(45980500001)(43740500002);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?q?RR7MP9Im1dh0y4xG84uWqv/0aPB1?= =?utf-8?q?EW+kv1aVqZ241wHFp+zJdUZaXW5l75wo2b6NCpjEmdVEs7BG7BhwgNNe+osiJC+pP?= =?utf-8?q?tnpJVpgDiyUO766+nn259dMp8O2SNoTb/ytWaSxwao2HyutFGY0GAYzDtbXL2ciKW?= =?utf-8?q?uJaAqUDTp2kHiysjXCHDBuGr/IVxSbbQAX/aCvW18x4IC2Xqb+6HUHPXp40U5HKRJ?= =?utf-8?q?ENet4+oAI23fPvOmHNdjYlPg4nFuNk2LwbnAlgruyaAER1ggngKav1xQLaRzEjMMz?= =?utf-8?q?Um9G/q2qGl4+rm4dvUe5PQp9u5bPHa5ZtZWZlL8iriHP5aoiJMx0kl0rErTmYytpN?= =?utf-8?q?YpYeGFqreEV17x/fR4vRrqjmECBUrexNtsWsAlLLx68tE5wbZ5TQgi+O7kRtqYMgy?= =?utf-8?q?UzRqp2gL6ZSxJ1c0iYvDUoBpWEW6HXyatjyhUetEzPDxVOLaeC319BKfgg+FsBopo?= =?utf-8?q?w8XWI0Twp2SIaopl2cbe42i5lGc+yC6FimduVQCLunXV+Dl+uExcrXrLKDESTq1jT?= =?utf-8?q?M9kEeNkMAzyheB8JFKmoZqARNu9BggvGzYzwqPA1AKHYfL4KGURRX7xv6pC/somXq?= =?utf-8?q?y4Gnxm7+eLXn8VugIxctKLxqRalfja3VwFaP8FAZksPeQiTkxHFJFRE0rUoFkMXo1?= =?utf-8?q?Dz6WTK+ud9tyQspOFaMg2mOXd+ov1lMkkB8scZUHtWePp6E/hwbq++1hetW0OLaYH?= =?utf-8?q?uJhT+oqEiedhgViUqa3wQKlxV9hlHXFZzDJ+OescemjNg7G1MgjAKsaozODTlzMjd?= =?utf-8?q?peHCYLKyDnqvVdpZtw/HiuPW9KNZ+QshPKLMJFBIEbp6YFvMBhK5SSz8BOLgB5OuN?= =?utf-8?q?yhqKaEuy/F4JAhDbGmn484qYIf6aXv3wUlT2H7TSlHieb7hG1jaFDUELFJO1UkhV3?= =?utf-8?q?7BxLssg5aQNyw6phVRzYi6oXsXXHk29LjkiptcR0dyRQBPtckKlFEOWJ7YYR4oyaA?= =?utf-8?q?UBMD9Kop7e4ZtTE9/yPyqu5hM494sNWq15mFRFjjRJuFnCHLGo2x7nf4Z3ZGRwVtI?= =?utf-8?q?HLSHm23fZZxYAi/hFmdDYiviQgUqOYQLpU6kd49pmdR3KkWg3I8qQTzjAA9Vv8pKv?= =?utf-8?q?pF1kZMHC1rEsOkBgxTE0McwIbzhyxh1ctlRjdsH+keHhB9Txeys6Cf91NnFyp5FSZ?= =?utf-8?q?tLOjL9UPdsuKBhRGcUfPWGUDFaA6D7WkpOCkrq80GfP8HmsP7Sk3mkfvxDMrQK+CE?= =?utf-8?q?ev8ZcRWZoNhwV6lmp+g4XlUgbaQXb608UlUtrZqZk+9vOZFsWF5nU4yIz8UwmyjZO?= =?utf-8?q?e0Ne/s6dyu+mY28MhmKm5oVmeD6NOTaO4Bs2C/jTOJ94eglmhgFFdwSB0Ghr+2o4h?= =?utf-8?q?5X4BhGyWrJjyuWunSOvsE37F/TpfU86oTusi6MKB9QuvP7u5SPkLS8FhKGuvi/Ba6?= =?utf-8?q?a0WOhmF1qlL26OvkCbD4KlN1VVPvxFX5ix+mGG0LyP076+N0AoNOtL8FYNFNuA/IJ?= =?utf-8?q?TEHgOElHzOOIZSJd8odN/P7QMk+ORyeB9bTd8jXoByVefQOsLtcX4uGSI9BOiYJKo?= =?utf-8?q?JCUGAzuz9A+j?= X-OriginatorOrg: suse.com X-MS-Exchange-CrossTenant-Network-Message-Id: e3521cb0-c010-4e9a-a511-08db0ab2e393 X-MS-Exchange-CrossTenant-AuthSource: VE1PR04MB6560.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Feb 2023 15:32:44.3180 (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: Z3wabkzpCjij8RmqUOz43w8QwHPkbEzkEs3B/zydR5U1cS/5ljI7BRYAGgN3qsFgs1ekyz7FM80xoXHFUqF0rQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM9PR04MB8274 Just ahead of the logic in question we've translated the subject MFN to a valid original GFN, in order to then translate that GFN back to an MFN. Restricting the call to p2m_remove_page() to the case where these two MFNs match is too weak. Instead refuse the operation altogether when there's a mismatch (which likely indicates a bug elsewhere in Xen), by leveraging the checking in p2m_remove_entry() via passing in the expected MFN. Signed-off-by: Jan Beulich --- If we were certain that a mismatch indicates a bug elsewhere, we might want to consider crashing the domain instead, to limit damage as well as to make sure the issue is actually noticed. --- v2: Drop the check rather than separating it out. --- a/xen/arch/x86/mm/p2m.c +++ b/xen/arch/x86/mm/p2m.c @@ -719,8 +719,7 @@ p2m_add_page(struct domain *d, gfn_t gfn ASSERT(mfn_valid(omfn)); P2M_DEBUG("old gfn=%#lx -> mfn %#lx\n", gfn_x(ogfn) , mfn_x(omfn)); - if ( mfn_eq(omfn, mfn_add(mfn, i)) && - (rc = p2m_remove_entry(p2m, ogfn, omfn, 0)) ) + if ( (rc = p2m_remove_entry(p2m, ogfn, mfn_add(mfn, i), 0)) ) goto out; } }