Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH] drm/amdgpu: fix warning for overflow check
To:     Arnd Bergmann <arnd@kernel.org>,
        Alex Deucher <alexander.deucher@amd.com>,
        "Pan, Xinhui" <Xinhui.Pan@amd.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Chunming Zhou <david1.zhou@amd.com>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, llvm@lists.linux.dev
References: <20210927125824.1583474-1-arnd@kernel.org>
From:   =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>
Message-ID: <a27a9db3-1186-8fea-8952-fca4171bcee5@amd.com>
Date:   Mon, 27 Sep 2021 15:07:13 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.13.0
In-Reply-To: <20210927125824.1583474-1-arnd@kernel.org>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
Content-Language: en-US
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?cGdOTW5ISTJ6Q2lLcGhsdUg4R0loWTVCbTVVT1E4VjNCZ3J4aEgzek5VMDlh?=
 =?utf-8?B?bzJZV1JQUmlyVlRwY3d2RW9tYXZQTDJDZUt1Tm5qSU85RkhEVU5mYlp0QzJk?=
 =?utf-8?B?MHBGZEpRZmYyR01wQk5vaStFbDNibTVFZFhybjJGZ3oweHlnck1kc2swRnVL?=
 =?utf-8?B?MHVKejhlMDVVd0szM0ZFSUlmUVNqUytHRFdPMlNvYmlDcEdUTExHMW4za0Mz?=
 =?utf-8?B?RHBsTjdkb2FhcWRQcGs0Ukk4NElVRDE4UitRQ3E4d2RqbHpuVWZ2ekdXb2Zx?=
 =?utf-8?B?L0NzZ29wdFBhdUpVZXpZaDVDb01EeE5rc3ljUGtrenpva0FyakRVLzNTcDdE?=
 =?utf-8?B?Z0xOL2hxZXZoaW82WC81QjRqYzVoOHZpRXpGeDZCdWxXb2lIaXdqYjBLclhq?=
 =?utf-8?B?ZU9jd0JZMG5yWHVqeGJYYWx5S2I5cExZQzZ3OVFmTmJ1OE8rYU95MDlWSnhQ?=
 =?utf-8?B?bzBkMkVUV3Y2L2Q1VnRIS1FrQ2pWT282UE9mellkcU9sNzlPRUJlYVp2K0ZT?=
 =?utf-8?B?a3cxUStHamcyUkp3amZFdFlsTVhQQi9XRXJIZCtRVTNZeGlmditYbXo2djVH?=
 =?utf-8?B?Y3dmamw0a3dDR1gzUmp2OTBMM0p4TjJ1Ny9iWXFLUHlNYjV3UXNEbGpTUmxa?=
 =?utf-8?B?S1A5R3Bxb2hwMnU3ZDRaUCsyZnNuZ0FXSGYvZERYSU93YXpKY3E5SklocXZ0?=
 =?utf-8?B?WjRhWk1IeUNtbndib2YwQWFvQkx4dUhKM1JIUWE1bVVlNlZJeGxCd1FYblFY?=
 =?utf-8?B?SEN6cTc1WFI3US83c2d2aXdoSXl4bXFJTFcyd0tVeFF1NTRLbEdySjAwaThE?=
 =?utf-8?B?UHduSzBMWFpFSUp5NW9Wcm5OTktTdnpvSkhWTDQ0Y0VyYlFKbjdUZ0dEZWNs?=
 =?utf-8?B?UDVhRS83M0tJOVVuTndsb1RaRHMzcXJkZzdaa3BDNmJIMWhtZ1czZ2ZhYm5v?=
 =?utf-8?B?RlNXSTRJMFBJOXJKVTIwTlRSUjJ0K3I0aUFVSG1uYXcrWE5qeDMxSUo0bXNx?=
 =?utf-8?B?V3R6YXZiVHZ6VmwxdHhzdmNDNDRFb2VWUDUrVWRtRDFRZzFzTldnd1dkVmFN?=
 =?utf-8?B?ZDNCWDVlMVA5K3RmbXNFSzk0UEpGdDdWTzZjbXR1Ym4zeDdTWG0rNXZpTEJp?=
 =?utf-8?B?MnY2QTUrbmR2d0ZudktmWE9USE9KVkRaV3YxODFiYUNoYlZ2TE1JTGMxbnRG?=
 =?utf-8?B?TkgrNmtFTWdjOVV6N1EvRWhJemh1SHNORG1WMWI0dHdySkVqK3Y4cVdNelA1?=
 =?utf-8?B?aUdxSGZaaEFabDRPUnBaaTVsR1EraTRrWjA3RFVqUytNaDZzUlVNUTlSNnNv?=
 =?utf-8?B?NDZWQ3VQYWk0ai9uTkhncTVYMHN4NWtJdTVtN2hmdkFienpmeURpV3diTW5Z?=
 =?utf-8?B?S3BQY3NWc3d1dTdYS3d4Nkk3TnBvVHI4MjY0TW8ramlQTWlCVkV6cC9YQW5U?=
 =?utf-8?B?bktnbWRXaXI0b2Znc1lJOTQyMnhvdU1sSWtieW1URTNYT0o4bEROajFORXJt?=
 =?utf-8?B?RzJydWxtb1cxaXNKc0JtY2VhZUdjY0JZdTFKZTZibWZLR2ZuaWZ3NHJQTWtX?=
 =?utf-8?B?OEMvaDhxYlVXcURzSkRiN25BT2pFRFFCOVR3Y3d6TXROalh0RWszS3k2Wk16?=
 =?utf-8?B?VVV2VFRpTk4wRDBrYjhuQ1pnVzd4bnQ4K3BlQXBFYW43T2FET3cvOTJDTm12?=
 =?utf-8?B?SVU3OVVXRm9QWldwaWNoVnZhbzBpN2haeHpRR0tlVllRVWlNMWpaT3ZFWm92?=
 =?utf-8?Q?fRscZfKJHczFmo4ASB6hiKwxHnnCwc++sRtvSLM?=
X-OriginatorOrg: amd.com
X-MS-Exchange-CrossTenant-Network-Message-Id: c614c8bf-630f-415c-daa3-08d981b7be0c
X-MS-Exchange-CrossTenant-AuthSource: MWHPR1201MB0192.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 27 Sep 2021 13:07:22.1865
 (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: 18j7vu7pt+Tg0B35T2AN+WfWf/ms0W05jvlvfR2SRHQYX0WYKBTPsFtgJFF50RZZ
X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR12MB1214
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Am 27.09.21 um 14:58 schrieb Arnd Bergmann:
> From: Arnd Bergmann <arnd@arndb.de>
>
> The overflow check in amdgpu_bo_list_create() causes a warning with
> clang-14 on 64-bit architectures, since the limit can never be
> exceeded.
>
> drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c:74:18: error: result of comparison of constant 256204778801521549 with expression of type 'unsigned int' is always false [-Werror,-Wtautological-constant-out-of-range-compare]
>          if (num_entries > (SIZE_MAX - sizeof(struct amdgpu_bo_list))
>              ~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> The check remains useful for 32-bit architectures, so just avoid the
> warning by using size_t as the type for the count.
>
> Fixes: 920990cb080a ("drm/amdgpu: allocate the bo_list array after the list")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Reviewed-by: Christian König <christian.koenig@amd.com>

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c | 2 +-
>   drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h | 2 +-
>   2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
> index 15c45b2a3983..714178f1b6c6 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
> @@ -61,7 +61,7 @@ static void amdgpu_bo_list_free(struct kref *ref)
>   
>   int amdgpu_bo_list_create(struct amdgpu_device *adev, struct drm_file *filp,
>   			  struct drm_amdgpu_bo_list_entry *info,
> -			  unsigned num_entries, struct amdgpu_bo_list **result)
> +			  size_t num_entries, struct amdgpu_bo_list **result)
>   {
>   	unsigned last_entry = 0, first_userptr = num_entries;
>   	struct amdgpu_bo_list_entry *array;
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
> index c905a4cfc173..044b41f0bfd9 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
> @@ -61,7 +61,7 @@ int amdgpu_bo_create_list_entry_array(struct drm_amdgpu_bo_list_in *in,
>   int amdgpu_bo_list_create(struct amdgpu_device *adev,
>   				 struct drm_file *filp,
>   				 struct drm_amdgpu_bo_list_entry *info,
> -				 unsigned num_entries,
> +				 size_t num_entries,
>   				 struct amdgpu_bo_list **list);
>   
>   static inline struct amdgpu_bo_list_entry *