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R. Silva" , Evan Quan , Alex Deucher , David Airlie , Daniel Vetter Cc: amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" References: <20200519225545.GA2066@embeddedor> From: =?UTF-8?Q?Christian_K=c3=b6nig?= Message-ID: <1065d63e-7959-e4b4-af4e-70607ba92296@amd.com> Date: Wed, 20 May 2020 09:42:27 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 In-Reply-To: <20200519225545.GA2066@embeddedor> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-ClientProxiedBy: FR2P281CA0007.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:a::17) To DM6PR12MB4401.namprd12.prod.outlook.com (2603:10b6:5:2a9::15) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [IPv6:2a02:908:1252:fb60:be8a:bd56:1f94:86e7] (2a02:908:1252:fb60:be8a:bd56:1f94:86e7) by FR2P281CA0007.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:a::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3000.25 via Frontend Transport; Wed, 20 May 2020 07:42:34 +0000 X-Originating-IP: [2a02:908:1252:fb60:be8a:bd56:1f94:86e7] X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-HT: Tenant X-MS-Office365-Filtering-Correlation-Id: 5a229a49-9264-44a6-bf49-08d7fc915d0e X-MS-TrafficTypeDiagnostic: DM6PR12MB4468: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:826; X-Forefront-PRVS: 04097B7F7F X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 2fOwndbdznGsA0HdcWuFiFzp2eL0xRUcR4XGZHk68y8/ibVkfWp8WQ1+SFywM1MhTxxlWg75IBn/M5ahnduy/VL6K43iWysbaY97ZNPqW3o8NBb8i/p7Bv+2EAUVXbZg+y9A6jcqx8DvrWDdiejj4fanal0RkI1nnAQeCMtQFBN+WVFRy6P1ZIdj7ObRrrv3q8fdqXBq6J9o9MHtlI34uUxGvwScuH6TYAwpkvw9yEkGd1kU6jsa54Sx6UHAlFSLxW+EGweeMO4zLs3QItrFF5dciiuYT9K4UWdrgEAniH0oWjIngIpRAitG2IDeFfrpSkkDKRVaiuwQ7zt3ejmm2VwkmCKeKeSE10JrMetjcHRzWzteys6+3iGIORZI+y8MZ5Cx3UrHTDqcIEJmLKo1bUVTjrG6rBQ/KRaKO5sWpkVZu1YGPFR/NYmtiJtxOCUfs8c3c2PaPO8g99mmJNNWrA== X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DM6PR12MB4401.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFTY:;SFS:(4636009)(346002)(39860400002)(136003)(366004)(376002)(396003)(45080400002)(66574014)(31696002)(5660300002)(966005)(6666004)(86362001)(52116002)(2616005)(16526019)(4326008)(478600001)(186003)(316002)(6486002)(110136005)(8936002)(36756003)(31686004)(66556008)(66946007)(66476007)(2906002)(8676002)(43740500002);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData: 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 X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 5a229a49-9264-44a6-bf49-08d7fc915d0e X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 May 2020 07:42:35.8964 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: +zDK610TnFFTu7NSNqzpIWsxRameozes6TxDZD02bwt5mvEySj7UBsWiGQT1KT62 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR12MB4468 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 20.05.20 um 00:55 schrieb Gustavo A. R. Silva: > The current codebase makes use of one-element arrays in the following > form: > > struct something { > int length; > u8 data[1]; > }; > > struct something *instance; > > instance = kmalloc(sizeof(*instance) + size, GFP_KERNEL); > instance->length = size; > memcpy(instance->data, source, size); > > but the preferred mechanism to declare variable-length types such as > these ones is a flexible array member[1][2], introduced in C99: > > struct foo { > int stuff; > struct boo array[]; > }; > > By making use of the mechanism above, we will get a compiler warning > in case the flexible array does not occur last in the structure, which > will help us prevent some kind of undefined behavior bugs from being > inadvertently introduced[3] to the codebase from now on. So, replace > the one-element array with a flexible-array member. > > Also, make use of the new struct_size() helper to properly calculate the > size of struct smu10_voltage_dependency_table. > > This issue was found with the help of Coccinelle and, audited and fixed > _manually_. > > [1] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgcc.gnu.org%2Fonlinedocs%2Fgcc%2FZero-Length.html&data=02%7C01%7Cchristian.koenig%40amd.com%7C8a400bdb88924a1d951508d7fc471966%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637255254622039268&sdata=ILOPPn17c%2B3oyLLdh%2BgH2b%2B8RdhWuTFGxruRD7GUHOo%3D&reserved=0 > [2] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FKSPP%2Flinux%2Fissues%2F21&data=02%7C01%7Cchristian.koenig%40amd.com%7C8a400bdb88924a1d951508d7fc471966%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637255254622039268&sdata=lCr5Otij55Snq27BDp4RmtW4hNhOS%2Bm4vSUOOAz07XA%3D&reserved=0 > [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") > > Signed-off-by: Gustavo A. R. Silva Acked-by: Christian König May I suggest that we add a section how to correctly do this to Documentation/process/coding-style.rst or similar document? I've seen a bunch of different approaches and some even doesn't work with some gcc versions and result in a broken binary. Thanks, Christian. > --- > drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c | 6 ++---- > drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h | 2 +- > 2 files changed, 3 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c > index 246bb9ac557d8..c9cfe90a29471 100644 > --- a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c > +++ b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c > @@ -410,12 +410,10 @@ static int smu10_get_clock_voltage_dependency_table(struct pp_hwmgr *hwmgr, > struct smu10_voltage_dependency_table **pptable, > uint32_t num_entry, const DpmClock_t *pclk_dependency_table) > { > - uint32_t table_size, i; > + uint32_t i; > struct smu10_voltage_dependency_table *ptable; > > - table_size = sizeof(uint32_t) + sizeof(struct smu10_voltage_dependency_table) * num_entry; > - ptable = kzalloc(table_size, GFP_KERNEL); > - > + ptable = kzalloc(struct_size(ptable, entries, num_entry), GFP_KERNEL); > if (NULL == ptable) > return -ENOMEM; > > diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h > index 1fb296a996f3a..0f969de10fabc 100644 > --- a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h > +++ b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h > @@ -192,7 +192,7 @@ struct smu10_clock_voltage_dependency_record { > > struct smu10_voltage_dependency_table { > uint32_t count; > - struct smu10_clock_voltage_dependency_record entries[1]; > + struct smu10_clock_voltage_dependency_record entries[]; > }; > > struct smu10_clock_voltage_information {