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] gpu: ttm: fix GPF in ttm_bo_release
To:     Pavel Skripkin <paskripkin@gmail.com>, ray.huang@amd.com,
        airlied@linux.ie
Cc:     dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
References: <20210707185108.3798-1-paskripkin@gmail.com>
 <f4bb7b29-3abc-a056-fc24-4e91b5de8d74@amd.com>
 <20210708113701.4cea7989@gmail.com> <20210708130910.63a15c73@gmail.com>
From:   =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>
Message-ID: <55aa8ece-1f1d-76d0-4f2f-951d39e79484@amd.com>
Date:   Thu, 8 Jul 2021 12:56:19 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.11.0
In-Reply-To: <20210708130910.63a15c73@gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
Content-Language: en-US
MIME-Version: 1.0
X-MS-Exchange-MessageSentRepresentingType: 1
Received: from [IPv6:2a02:908:1252:fb60:bc19:c1e3:6307:7e3e] (2a02:908:1252:fb60:bc19:c1e3:6307:7e3e) by FRYP281CA0007.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4331.11 via Frontend Transport; Thu, 8 Jul 2021 10:56:23 +0000
X-MS-PublicTrafficType: Email
X-MS-Office365-Filtering-Correlation-Id: 6999aa2d-6375-4577-0123-08d941ff06f0
X-MS-TrafficTypeDiagnostic: MN2PR12MB4320:
X-MS-Exchange-Transport-Forked: True
X-Microsoft-Antispam-PRVS: <MN2PR12MB43207F2CE75E1EC9980D19ED83199@MN2PR12MB4320.namprd12.prod.outlook.com>
X-MS-Oob-TLC-OOBClassifiers: OLM:10000;
X-MS-Exchange-SenderADCheck: 1
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:MN2PR12MB3775.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(396003)(39850400004)(346002)(136003)(366004)(376002)(478600001)(2906002)(38100700002)(86362001)(186003)(83380400001)(36756003)(2616005)(31686004)(6666004)(8676002)(66476007)(66946007)(31696002)(4326008)(316002)(66556008)(5660300002)(66574015)(6486002)(8936002)(45980500001)(43740500002);DIR:OUT;SFP:1101;
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?ZzdNNlNuaFl0NUdkUTV2VXVpdjRTRysxVUVnbVRuL1pUcGhRYW9FSGp2VXNr?=
 =?utf-8?B?K1ZTcDZXZ2xVUkFDUUJaUkV6MHE3ZFVyVGZ6TmQ4THNBMi9Pc0NNREUrVCtm?=
 =?utf-8?B?OTdUbDZPUjhCMXl2Q0tMVWpPdEFDd0Q2QUdxcURjOTQ2elpLREthbXhqQlZh?=
 =?utf-8?B?bTlmOW0zNXBCQkZ2dHNrMVp2dnkwVFYrUDRmOHNhL1JPYVEzaEhuLzYzZWFN?=
 =?utf-8?B?TjAwaDNtZTQ0bXlyRjhiaEhUdVpiNTZ6bWZhQmlpWE5LVlhUL3VuS29ydUpl?=
 =?utf-8?B?ZFVmNWZPa3VsY3UvKzlJOHhqOXdUcmxkdDhWVkx0enJicThjdUREb1RYeG5h?=
 =?utf-8?B?QmVCakFaMURMQ0VkVnFmSDV0bFhJUUp0eHlvaWRWK0xMUVJXYktUd3B2MjJZ?=
 =?utf-8?B?OU9hZEFlYlkzT1dmTnNPZ3RKTXI2MmswSEJqT2JqN0cxOGVXQi9IcG04SEQw?=
 =?utf-8?B?SUovbFlndkwxaG5EcURJeDJpR3BYa2REeHZLNVMrU1ExMXR2ckZzSUlUYUps?=
 =?utf-8?B?d1N5K2xjcWhnT2RMSnlTYWlHUzdsQUp5a3ZMOXFxbFpWdVUvVGNvMTdjZERQ?=
 =?utf-8?B?anNKR2xJSTFoUUh0ME5ERnkxbUk2R3pybWE0dllSdmtqR3ZnV2JXRVI1ZUR1?=
 =?utf-8?B?RS9lWm10ZzRicE1na2RsNDNteGF1V01ONWx2d2hCNFNlOGUvVWJmZUJMRXps?=
 =?utf-8?B?eG4yb0N5SDFmZkI1NFFTTDRIVzd6azlCNHZZS0xZNzR1R0N3WVNocE5Db09D?=
 =?utf-8?B?Z1ZiK3dKQ1RUcEhNUjhucjViT3owdmg1dThKMzIyUGswUytLcXBZSW5HVDVM?=
 =?utf-8?B?WTFiYmFhNlZQeHUzUVFydlZHeS8ySGxzNEhnbWZyRVhkSDMyWUNPUUI4ZndI?=
 =?utf-8?B?MmJCVXRFZEF2MHlQVHF1RHpLRXdUSWJEU0x6SDRHYVIzdzhtMnZqcEZPSTVi?=
 =?utf-8?B?RGlYS1VZcHMrYk5hUmpnOElBMjdoeGFTdktDZWxoeTJaSjhTZDBOQmhkZ3k5?=
 =?utf-8?B?ZlpSa1NVVm5zMDlRMm9uaHd2VlBEcC9vdFpKNFdUMnI0UEt3Rk12Rlcwc3dJ?=
 =?utf-8?B?VnQzS0I5bEhYZFkzdDE1VlhCUDlHMmd0YVZPUFdwcTAzSWI0NzVrRVlKZlYv?=
 =?utf-8?B?WVo0Z1podnllbkhMQk5Vb0FEdnRWbzIzQ2wzemZuOFN3bmxpR1NoT2Q2bExE?=
 =?utf-8?B?d0ROaWxZM3BsWlBHU1V6ZWdabVk3N3hFejJEQytkVm4xcXBVTkFUNytSam5q?=
 =?utf-8?B?SlIzZnArVjdsbmdZK2lOT0x2QUsxd2NteDdla0h4SWJWRXdUd1laaENFY0Ra?=
 =?utf-8?B?STB2SG1ONHFqRkRNSEFaMSsyWEs2R2VuQU9XRVR5dmRzTytwT0F3bmhiR25S?=
 =?utf-8?B?OWJyalJoNXFncmNwUkQxWFQvSEtaNlp0bGo0end3Uy83TU9HQUEyWXpmTTlF?=
 =?utf-8?B?Z3hiY1p4WXc1Vk95ZVFFdDNydm9KZ1JydjJHTGlSQ1JmMEFDdWJiUTQwT3Jh?=
 =?utf-8?B?U2JUYUU3YndsdEJ6cEd1aXFLMVMwbmJRWGI1SThHMkxPUGtKMmw0UlMyL0Nw?=
 =?utf-8?B?OFoxa0E3R0IyTG41QTlyMzBpUXJ6SEU4VGpjK21XcjlyUG9BK2psWUNZZGk5?=
 =?utf-8?B?aVhjd1dSaTBHNmd3bjlRekQrQXFJUWcvU21XeGFtWURBVGZ3RXd5bER2N2lE?=
 =?utf-8?B?OXNBaWZ4ZlRheklDQ0JIb0NzY0gyNDVva3BhSkZCZDVCQ3BkQ1M1SGtXWVR0?=
 =?utf-8?B?L1ViRk5ZRW0yYlhVbXgrZ3hDZ3dJNGxaMU53blY3NWRGaEdlYVFJZGtoRDJo?=
 =?utf-8?B?RVh3RzFhemc1NldUdU5OdS9wL0ROejM2Zi9FMGRBVFQ2TG0yLzVVcTE5dmVD?=
 =?utf-8?Q?09rjNWWuEnc8e?=
X-OriginatorOrg: amd.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 6999aa2d-6375-4577-0123-08d941ff06f0
X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB3775.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Jul 2021 10:56:24.0153
 (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: ZNTYJCdNTcrFwXQK/tutRgv1iKO6acTomEPfangjWddOrW8iF5iLfn1XQmDqHnur
X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4320
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Am 08.07.21 um 12:09 schrieb Pavel Skripkin:
> On Thu, 8 Jul 2021 11:37:01 +0300
> Pavel Skripkin <paskripkin@gmail.com> wrote:
>
>> On Thu, 8 Jul 2021 08:49:48 +0200
>> Christian König <christian.koenig@amd.com> wrote:
>>
>>> Am 07.07.21 um 20:51 schrieb Pavel Skripkin:
>>>> My local syzbot instance hit GPF in ttm_bo_release().
>>>> Unfortunately, syzbot didn't produce a reproducer for this, but I
>>>> found out possible scenario:
>>>>
>>>> drm_gem_vram_create()            <-- drm_gem_vram_object kzalloced
>>>> 				     (bo embedded in this object)
>>>>     ttm_bo_init()
>>>>       ttm_bo_init_reserved()
>>>>         ttm_resource_alloc()
>>>>           man->func->alloc()       <-- allocation failure
>>>>         ttm_bo_put()
>>>> 	ttm_bo_release()
>>>> 	  ttm_mem_io_free()      <-- bo->resource == NULL passed
>>>> 				     as second argument
>>>> 	     *GPF*
>>>>
>>>> So, I've added check in ttm_bo_release() to avoid passing
>>>> NULL as second argument to ttm_mem_io_free().
>> Hi, Christian!
>>
>> Thank you for quick feedback :)
>>
>>> There is another ocassion of this a bit down before we call
>>> ttm_bo_move_to_lru_tail() apart from that good catch.
>>>
>> Did you mean, that ttm_bo_move_to_lru_tail() should have NULL check
>> too?

Yes, exactly that.

>>   I checked it's realization, and, I think, NULL check is necessary
>> there, since mem pointer is dereferenced w/o any checking
>>
>>> But I'm wondering if we should make the functions NULL save instead
>>> of the external check.
>>>
>> I tried to find more possible scenarios of GPF in ttm_bo_release(),
>> but I didn't find one. But, yes, moving NULL check inside
>> ttm_mem_io_free() is more general approach and it will defend this
>> function from GPFs in the future.
>>
>>
>>
>> With regards,
>> Pavel Skripkin
>>
> I misclicked and sent this email to Christian privately :(
>
> Added all thread participants back, sorry.

No problem.

Do you want to update your patch or should I take care of this?

Thanks,
Christian.

>
>
>
> With regards,
> Pavel Skripkin