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dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=nvidia.com; Received-SPF: Pass (protection.outlook.com: domain of nvidia.com designates 216.228.117.160 as permitted sender) receiver=protection.outlook.com; client-ip=216.228.117.160; helo=mail.nvidia.com; pr=C Received: from mail.nvidia.com (216.228.117.160) by CY4PEPF0000FCC5.mail.protection.outlook.com (10.167.242.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7784.11 via Frontend Transport; Thu, 25 Jul 2024 12:59:45 +0000 Received: from rnnvmail201.nvidia.com (10.129.68.8) by mail.nvidia.com (10.129.200.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.4; Thu, 25 Jul 2024 05:59:34 -0700 Received: from fedora (10.126.231.35) by rnnvmail201.nvidia.com (10.129.68.8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.4; Thu, 25 Jul 2024 05:59:29 -0700 References: <8b06dd4ec057d912ca3947bacf15529272dea796.1721749627.git.petrm@nvidia.com> <87o76n85ml.fsf@nvidia.com> <877cd98woh.fsf@nvidia.com> User-agent: mu4e 1.8.14; emacs 29.4 From: Petr Machata To: Petr Machata CC: Eric Dumazet , "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 14:56:47 +0200 In-Reply-To: <877cd98woh.fsf@nvidia.com> Message-ID: <8734nx8w6s.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: CY4PEPF0000FCC5:EE_|MW4PR12MB7238:EE_ X-MS-Office365-Filtering-Correlation-Id: c361fc36-6c4e-4ea0-256f-08dcaca9a83f X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|82310400026|36860700013; X-Microsoft-Antispam-Message-Info: =?utf-8?B?MGlHczVHMVJ5MExNSEFvb2IyL2IwNXRmZnBJYks5d0dyV3FUd0hsME5IK2RK?= =?utf-8?B?RndrT0djb3hNRWlWdG4zWUZrMnZTZ2ZRMDBWRFBqRHJ4U3R3Q09JcmpocFp4?= =?utf-8?B?TFNVelJHa09JYU1laENUTUllaWY5KzZsNW5XeEUrU3NyOHVyanZQQUV4MzNH?= =?utf-8?B?Z0NQbnRYalU4cFdFeW5HbkhLalhVd0lNRmU0TGF1UmxOVWRxa2NjV0E4Y1Nh?= =?utf-8?B?b09iRjVsNE5lcElScGF2c3BYODJTR3V0QXRYQWxHZEorSnROY0VtQWxMUzJU?= =?utf-8?B?T0tpekR1bUk0NEhKY3lQdkJjV2lUVWJaZG9hNmV4K2xVRzFUTkdLWGQybWpi?= =?utf-8?B?ZDM4czd1THFJS1pEN2ZycTFoU0hWWkdMUUdXUitjOURRS0lHQnAyNHdlMnZL?= =?utf-8?B?WUtCNnp3MW5nRjJ3czhaNjdpWThpVkx4bklsOXNidkdvWmdqOWpCNGRjU01h?= =?utf-8?B?bHdPMHFrTXdVcDRNaC9ETEtYYzI3NWxSSFk3RnFzakVWWWVYeXMrRDFBNktm?= =?utf-8?B?Qkp1a21TalYvdjRnVE45Y00xajIxcmVPcmY2Zlp6N0FBaE1PY0N6OFREWXJ3?= =?utf-8?B?TDV2azlzYi81NVc1aVpzYWpMSm51dUFDTEJYai9MME83WUVJRHordFRsNG9a?= =?utf-8?B?RDVnekJiVUg3VVdacnJGQ1NGdjRFc0RXNE15MHU1MzM1Wk1ZU2JiT2RWT0lU?= =?utf-8?B?M0svQXdxNkp5TDU4Z0FrTmRYeG1TQ2pjMk1NeExVUG92OHRaVEZFMEFjOXhh?= =?utf-8?B?amIwcXBYRzV6R1RHWDR0dTZuWjFjTXZwNE85alpWb2hoMjYyNi9LUEVuWGVm?= =?utf-8?B?aTkzSkVqUnZ1U3lORU5FN3FPTDVaT2ZNa2U3TENMamtDekVmRkFqWWNWYzVU?= =?utf-8?B?VUVWTDZOZnpoMVBreDF3N1E1cVlhOWVLL3A4ZlZnNkk0bTlHdkphZlgwUTVG?= =?utf-8?B?QW54VytYWktvMjc0NzhQOElvWG1xQitYanI0RVZxOG9Ucms0UlZRKzlOeGNK?= =?utf-8?B?S093SGY0VkdpMGxWTkt6OXppOUVlMEhqalhiWkl4R2NXeG42cFIvdm9sdnNa?= =?utf-8?B?a3o5TVl4NDlWM1djZEd3dm0xUFplT3YwMjhFZDlabTU3V3IxUVJiZGNGZkhD?= =?utf-8?B?aWprVUlwYUdjKzh0M3B4VzZnOGJPaS96NkxJWDZKWWpEdmdjZVY1Z2tOcUhB?= =?utf-8?B?aFQwdDRqaURNRFNDdmNBbjdXSzd0bi9LWU45YUdoNGxleCtiR05hRDlCMjN1?= =?utf-8?B?SHp6RTFPZVR2R2dBR2RMalh4b1RLZUJZd3hTaCthUEhZa1pZZ3lPUDkvejJC?= =?utf-8?B?WGFUc1VsVFFta3lnTGhVZ3g5dE9UMHY5TzJMdkVhNW9HY1p0REhoUnNYYkJC?= =?utf-8?B?TjVHa3lhZVF0T2xMYjMyZzRMSXFyVE8rbytxcnhNU3I2VnJhempINUVmOWMv?= =?utf-8?B?ZUpNMHZwNTQ2amhrOG5MdDZYWFRkOFNoLzRZR0REdW5mUTRYV0Z0ZFBwVzZh?= =?utf-8?B?T1J4b0wvRkpiRDFpdHp6VGc0WW9JWmMweTJaQU9oZEZWZENqU3ZKaFZMelBS?= =?utf-8?B?VUxERzN0ZHkwMUVvOEVmRGlCU1NENWJRR1VSQkNzNGxtOUNYeHZOZ2h1cm0y?= =?utf-8?B?eXR5MmxUME9VOWZoZ3dHVnpSTDkzdE1kSVp2TFZkSEllamp1ZHlCcTBZQWJH?= =?utf-8?B?RmFQUnlRZXU1ODdkcHZUMUpTaXBiTC80VEZZZ0U0ekUrWXhhMHB4YW5BNlBP?= =?utf-8?B?cjlmaXpMUDZLZmMvNXM2VU4wVGorNVNPU3pLTDBZZXR6Y21LWnBwbG85VnB1?= =?utf-8?B?TDRockgycS85SlFuc1d6alRiL0VDYkdQUnlkWDVVU2dFNEZRUDBNdmsyUFdS?= =?utf-8?B?QWRBbDlXd1dCSTBJYjFoK1JQQmpWdG5sRUdOWi9ENDQ4MzRvZTk1TXUyZk1V?= =?utf-8?Q?TV0z+VzjVx0W/ZLvxXy2BE+P2cvHxicp?= 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)(1800799024)(376014)(82310400026)(36860700013);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Jul 2024 12:59:45.0835 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: c361fc36-6c4e-4ea0-256f-08dcaca9a83f 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: CY4PEPF0000FCC5.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW4PR12MB7238 Petr Machata writes: > 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 i= nitialized 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= =3D0x67}]] ...) =3D 52 >>> >> > > > >>> >> > > > The fields are reserved and therefore not currently used. But = as they are, they >>> >> > > > leak kernel memory, and the fact they are not just zero compli= cates 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. OK, Ido tells me this is just the "it's available on this arch" option and the actual option apparently needs clang. So disregard what I said.