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Message-ID: <96b0ebc7-4cd6-9053-06a6-78dfc0666b8a@suse.com> Date: Wed, 8 Feb 2023 15:40:37 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 Content-Language: en-US To: "xen-devel@lists.xenproject.org" Cc: Andrew Cooper , Wei Liu , =?utf-8?q?Roger_Pau_Monn=C3=A9?= , George Dunlap From: Jan Beulich Subject: [PATCH] x86/p2m: tighten old-MFN check in p2m_add_page() X-ClientProxiedBy: FR2P281CA0015.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:a::25) To VE1PR04MB6560.eurprd04.prod.outlook.com (2603:10a6:803:122::25) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: VE1PR04MB6560:EE_|PA4PR04MB9343:EE_ X-MS-Office365-Filtering-Correlation-Id: 329425c6-94a8-4030-a2d6-08db09e27267 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)(39860400002)(366004)(346002)(376002)(136003)(396003)(451199018)(31686004)(83380400001)(6486002)(36756003)(5660300002)(2906002)(26005)(186003)(31696002)(478600001)(6506007)(6512007)(41300700001)(54906003)(86362001)(38100700002)(2616005)(316002)(66946007)(4326008)(6916009)(66556008)(8676002)(8936002)(66476007)(43740500002)(45980500001);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?q?aB3DSe/+gtLebzOZJ2pk2I0TljM5?= =?utf-8?q?2n6jABEStagM7GzcJgvJBYkvorsenxDnr2StUt6JhwpYSaNPCznMpolCWuis6CNaY?= =?utf-8?q?+/cPFaZgr0NtKXhPWciVa0rGNtFP7Z2nIg2e+BCbTRikgStye14RaYTQrLzrg3lrG?= =?utf-8?q?5YxTZ/nM58QSvvh9BbqPatUAvc1ZEQ3K8Cpb9CU5pkgxwp197oWu9AZy4NmyzqSOp?= =?utf-8?q?Q7TVHGk+237vqX/W1uF0KQtkQsKoEFkpK4aC+8G84it7Zxbl7YUS2ZTUP70hp166k?= =?utf-8?q?jEa6oR0mnN0U6mQa6cR3wIgSU4jON/AfEmixJ5W+AUwGZnjgjLWOeVOOtqPTRNo8w?= =?utf-8?q?+G+bZN96RY8FjFd0s2jeLOV8+/YdjM0gxepVGCgMrXhQOocw+FtJ1tkH5YM6Z/kS7?= =?utf-8?q?now0jH2eYkqHQR//2tXaV86iLi8jPSwd2MiJEXD4A++evZWshLTmIzXSEDFlsOVTF?= =?utf-8?q?ay+OFrsze2bHGStJu6/8ZXZseT7Z52GscFUHI0bK9NGTIyJP19QSoc88NnZR6lclo?= =?utf-8?q?upSra3EcA55AYMoHZT+UH3sBtPSaoxXZFFSKxioVXNbTiz7eTZ82gMjOGFp+3P3cs?= =?utf-8?q?bpzZYq2izyKxEbiT+NcgmR2UqKxQMGKhSKwWaZqwNIJrebtWxFjBIOaf/3d2DDRgi?= =?utf-8?q?BbBiSNtugVj99f9pBeeiHE033rKKlztgHEzShShQHkgIhzVsoA70dNQNdZYHNXk/8?= =?utf-8?q?ixHC2pO8Y1VbDBkCM6fW2q2zn00CC5ukhc1UyqsLki+gd2WMJFsmW/GyY917gbUsc?= =?utf-8?q?26WFtdwuIhkr9grPec7HMgv2wCip7q1YIliH6TYsOTjfmxh1yi9sh0XKHh1Nts6zr?= =?utf-8?q?wX+vT6F2LIwg2/C95kJw9NAymqtC2yLdjColFrYd3V1JlYZDboA0i0Fq640TQIa1/?= =?utf-8?q?RLCRDeWtOmzgyNDuKyHKXAgHtRUjyjW6HvNpr3yB00map5ts8hFvHgKDq8PIr4Km9?= =?utf-8?q?dWOzz4ayey9yDRAHu40jUtMPiVMbTDlzcaSgFopizrMaHtWBw/DoTwu77PZ+XDEIk?= =?utf-8?q?I8oO9jh7dutsAOGLnVUtc2yBXbVfyb5g4lvvkjZ22zDy3dBFmLlcgnMwc8tij4Q2h?= =?utf-8?q?5nIYH+gu//YxFicYwXyeMPPD88xlDYU2YU+egTq6TTqhN0uaouadS1sPY+CrPN4KV?= =?utf-8?q?g4cA7oUlk2ElSbvfn/m7hrd2+2nNjE7BAfmRr9pobXnxfsutZ/29p2X0eoZUXgV/+?= =?utf-8?q?8wyClo8fmENp7buI7UN1li2KmlgZtqVRWzUrhicYNPjBKyqVkahlbe1wLtqgrA1+c?= =?utf-8?q?4bFnlhO69OUS25zMqDM6GTOyNOKqfCAmviKrJIZCcYewv9O/YxV2DsX30oHyiav8G?= =?utf-8?q?U7tmnYQDb9KU6iMiYcRgjyCHt9Qipde0eguoZZLgo7SpRRROMN0zGOAbcgoGTRUDT?= =?utf-8?q?3J4aDAleY0dkJin+Qf/ztVUNgp3WMhbhpZwqP5JrDs0hsvth4Muc5ncz/87MSyQj6?= =?utf-8?q?PuZ+Bm10SkIwbJXAf6ArjjqLIMBzL7ddpfjCGfWhIqZkbb6BvCpaxVuf9Wgs2R31K?= =?utf-8?q?ZfEPaM3iiMCC?= X-OriginatorOrg: suse.com X-MS-Exchange-CrossTenant-Network-Message-Id: 329425c6-94a8-4030-a2d6-08db09e27267 X-MS-Exchange-CrossTenant-AuthSource: VE1PR04MB6560.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Feb 2023 14:40:39.1272 (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: oblWzcvq5dAlDDDnWgZtGOFvQ6iaP/5c85oKwstmwc1/2Os4faazSHFwnNNipUqXIY93wPRJXPgX9pNWuOTqyA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: PA4PR04MB9343 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). 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. --- a/xen/arch/x86/mm/p2m.c +++ b/xen/arch/x86/mm/p2m.c @@ -714,13 +714,19 @@ p2m_add_page(struct domain *d, gfn_t gfn mfn_x(mfn_add(mfn, i)), gfn_x(ogfn), gfn_x(gfn_add(gfn, i))); omfn = p2m->get_entry(p2m, ogfn, &ot, &a, 0, NULL, NULL); + if ( !mfn_eq(omfn, mfn_add(mfn, i)) ) + { + P2M_DEBUG("old gfn %#lx -> mfn %#lx != mfn %#lx\n", + gfn_x(ogfn), mfn_x(omfn), mfn_x(mfn) + i); + rc = -EXDEV; + goto out; + } if ( p2m_is_ram(ot) && !p2m_is_paged(ot) ) { 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, omfn, 0)) ) goto out; } }