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emacs 29.4 From: Petr Machata To: Eric Dumazet CC: Petr Machata , "David S. Miller" , Jakub Kicinski , Paolo Abeni , , David Ahern , , Ido Schimmel Subject: Re: [PATCH net] net: nexthop: Initialize all fields in dumped nexthops Date: Thu, 25 Jul 2024 14:42:23 +0200 In-Reply-To: Message-ID: <877cd98woh.fsf@nvidia.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: rnnvmail201.nvidia.com (10.129.68.8) To rnnvmail201.nvidia.com (10.129.68.8) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CY4PEPF0000E9DB:EE_|LV8PR12MB9261:EE_ X-MS-Office365-Filtering-Correlation-Id: 3786083f-c1e0-4c49-38d8-08dcaca832eb X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700013|1800799024|376014|82310400026; X-Microsoft-Antispam-Message-Info: =?utf-8?B?aWx3TWVMU1hmM3BpWUMrUU1SclJCWEN2UFhIc1ZtS1p2V25TRCtKSXF4dTNG?= =?utf-8?B?c1FncEhlS3lHcnN3TEttSTNnSFhUUUcvVndlUGRpdGVSbEczbm90ckVpK28z?= =?utf-8?B?MVpZem12dk9KS0RVNFJ1MDFVcWRMS3pZdEZ2aTFENFNTdFZuUDBzY2JWM2NP?= =?utf-8?B?alRQYUk1eEo4c1kzYSs0SmMzWjFKWFhKVWhITlVFNWxSc28zMytsamx0YklL?= =?utf-8?B?M0szQXJ1M1o4S2JHK1l1ZlBEOW9naVpDSmVKekFEeG54WUlGY1lETlZsd09T?= =?utf-8?B?d3FrVjhadVQxejF3b0F1eEs3ZmlrTTNjTmxjMTNlaDkrRjh2d2VMcllpMDF6?= =?utf-8?B?MHQ4YzlkMFpTR3p1d2FnK0g4ZVhkdHRmWW5XUFBQWEpiU0lZWWl5VDc4Uk9P?= =?utf-8?B?K0NDU25Va1ZXN1VLdWxVWEFmdWJtQnRsbjVzZi9MOEcwWWpIUEJKRWVwWVl0?= =?utf-8?B?Q0xVZGx1d2lYdHAwNEVyTkQ3R2tHOS82QWNIYkc4cGFuTzN5dklIRnBGRXdm?= =?utf-8?B?TTVLVHFJU2ZkeFQvNzFGek5xVGN5UFJpSUlyVTdjdUZyWGJDSWNmK28yV2x3?= =?utf-8?B?akRCb2J4Mlg1VGg1MHdWZFdoc3JVWjE0WkxFemhCZ2l1VVJGck9qYWxRcDgz?= =?utf-8?B?R3FRZ0hsWG5CN0t0N2F5REZ5ZXEyM2lMWGdSRTczQ2RWb2IzTk5pSDl1VG8r?= =?utf-8?B?dis1cVlqZzVkWlpseC9VUXI2S0ZHeEhwaTJkWEw4ZGZDaytwRXpNdDZmNURI?= =?utf-8?B?Mmk2VWkrZVljOWR3WC9iU1hEOHQ5ZjdGYmRCclpyVFBMdmJPc0w2bnovcEJT?= =?utf-8?B?cVJtQkFHUS9zTUd2T0ZPV0FjSnFmTXhUUWdKQmJ4anBXWmN5TEZlVktTY2Rm?= =?utf-8?B?MXZ1NEc5Z0FrNUV4d0MzUEdlOEtNNkcvUU9mVjVLMFZ4eE56N0xzVG0vSFFX?= =?utf-8?B?SmFINWdoOWRuY2ZWa0RsS3lqWEgxRGZtc3VKbWRIV0tpTHF5Z2R1UW02bWNM?= =?utf-8?B?ajdBaDgrNFFjZlIvaW5lZWRrSW9PZjdVbkZnTldXN3FHL05OeXhnMk5ueXlk?= =?utf-8?B?dXA3cnhTODAwcnFCWFBQTmc5ZDZVb2ZEeklLVGtFb0VVTER2UEpYSktNRHhQ?= =?utf-8?B?eENsQk1SKzJHWlcvZ1hxV05WaklkWFM1UDZOcStiMk5hTWFQZ2gwWmRYTnlL?= =?utf-8?B?RGVobVdMQ0UrSWFQaHBPVFVBUEphTC9EZytrOXRCb1BmV1d4SHhPaHRsMCtv?= =?utf-8?B?UFZYSkF1ZjdqZXJ0eVc3SFRkQ1k2WVVFdi8wY0grSlc4R3Ztc3AySVBCRk52?= =?utf-8?B?TGFndURqTElmY0NhQjl3MUhMMitWd3dzTTA3SjVCQTk1WlVMR3N2dlFIa2Ir?= =?utf-8?B?Z1ViWi83cnVKL1hrWjQxMFFsNjE0N05NVWJHaTE2ZExHUEtIN0lMYUpjVDRw?= =?utf-8?B?NElyYXp5dDRLaGRMeHNsTnlkSXd0WFlJQnJBMFZZbnpvcVJTeHFLLzZqN0dq?= =?utf-8?B?d1VITDlMQVF3MnN3R2dQRndWelY3VUFqUXZtUHM2bmh4RVpYVWFWdmQrNStx?= =?utf-8?B?YlBMOE9BNUZ2ck9JZlF5NXBOUFVieW1xUU5tZ3pIbUthNlFhdG9RbDFDT0tY?= =?utf-8?B?U2F6RWMrUzVDZVRZMFVBaDl2QjFkOFNOQUM3bElVWnF1a0ZqZ1VONFh4TTNB?= =?utf-8?B?WHBaSmFTKzNySUlWYTdIUStEU1lIVHQ4ZWpGbnlOdXl2TDhYb085SUNCdnlk?= =?utf-8?B?L3NzVmVMOCs0TjRuK0lMK3FYQnBGZ2dxZHpmUUZwdFdLcGF4TjVCREJUeHBO?= =?utf-8?B?bTV5VmQ1NW5ZZW5HNjB5L3pxaUhSaHJsMFI1VGxxVXgrQ2w3Vld3WXRoV2dT?= =?utf-8?B?M1FzenZpeWFyTnVmL092VnNrUzI0SWxYbFllY1RORlRzdmN5RUljd0w4N3l6?= =?utf-8?Q?d84LbYDCCz9gpNqkgIcIcHUZ48+Eneeu?= X-Forefront-Antispam-Report: CIP:216.228.117.160;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge1.nvidia.com;CAT:NONE;SFS:(13230040)(36860700013)(1800799024)(376014)(82310400026);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Jul 2024 12:49:18.7746 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 3786083f-c1e0-4c49-38d8-08dcaca832eb X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: CY4PEPF0000E9DB.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: LV8PR12MB9261 Eric Dumazet writes: > On Wed, Jul 24, 2024 at 12:09=E2=80=AFPM Petr Machata = wrote: >> >> >> Eric Dumazet writes: >> >> > On Tue, Jul 23, 2024 at 7:41=E2=80=AFPM Eric Dumazet wrote: >> >> >> >> On Tue, Jul 23, 2024 at 7:26=E2=80=AFPM Eric Dumazet wrote: >> >> > >> >> > On Tue, Jul 23, 2024 at 6:50=E2=80=AFPM Eric Dumazet wrote: >> >> > > >> >> > > On Tue, Jul 23, 2024 at 6:05=E2=80=AFPM Petr Machata wrote: >> >> > > > >> >> > > > struct nexthop_grp contains two reserved fields that are not in= itialized by >> >> > > > nla_put_nh_group(), and carry garbage. This can be observed e.g= . with >> >> > > > strace (edited for clarity): >> >> > > > >> >> > > > # ip nexthop add id 1 dev lo >> >> > > > # ip nexthop add id 101 group 1 >> >> > > > # strace -e recvmsg ip nexthop get id 101 >> >> > > > ... >> >> > > > recvmsg(... [{nla_len=3D12, nla_type=3DNHA_GROUP}, >> >> > > > [{id=3D1, weight=3D0, resvd1=3D0x69, resvd2=3D= 0x67}]] ...) =3D 52 >> >> > > > >> >> > > > The fields are reserved and therefore not currently used. But a= s they are, they >> >> > > > leak kernel memory, and the fact they are not just zero complic= ates repurposing >> >> > > > of the fields for new ends. Initialize the full structure. >> >> > > > >> >> > > > Fixes: 430a049190de ("nexthop: Add support for nexthop groups") >> >> > > > Signed-off-by: Petr Machata >> >> > > > Reviewed-by: Ido Schimmel >> >> > > >> >> > > Interesting... not sure why syzbot did not catch this one. >> >> Could it? I'm not sure of the exact syzcaller capabilities, but there >> are no warnings, no splats etc. It just returns values. > > Yes, KMSAN can detect such things (uninit-value) But that would involve a splat. There's no splat with this issue, even though I'm testing on a CONFIG_HAVE_ARCH_KMSAN kernel.