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Thu, 10 Sep 2020 08:58:27 +0000 Subject: Re: [PATCH] drm/mm: prevent a potential null-pointer dereference To: Jing Xiangfeng , maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@linux.ie, daniel@ffwll.ch, nirmoy.das@amd.com Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20200910023858.43759-1-jingxiangfeng@huawei.com> From: =?UTF-8?Q?Christian_K=c3=b6nig?= Message-ID: Date: Thu, 10 Sep 2020 10:58:21 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 In-Reply-To: <20200910023858.43759-1-jingxiangfeng@huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-ClientProxiedBy: AM0PR10CA0062.EURPRD10.PROD.OUTLOOK.COM (2603:10a6:208:15::15) To MN2PR12MB3775.namprd12.prod.outlook.com (2603:10b6:208:159::19) 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 AM0PR10CA0062.EURPRD10.PROD.OUTLOOK.COM (2603:10a6:208:15::15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3370.16 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData: 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 X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 7653d191-cd8c-417f-1769-08d85567ae91 X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB3775.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Sep 2020 08:58:27.4510 (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: q5u58wATuqdeheLkf2QQnTcwcMxjTdXmXRrtEG8jCjUD7Mu7juk3aDTet1tQRag+ X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4125 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 10.09.20 um 04:38 schrieb Jing Xiangfeng: > The macro 'DECLARE_NEXT_HOLE_ADDR' may hit a potential null-pointer > dereference. So use 'entry' after checking it. I don't see a potential null-pointer dereference here. Where should that be? Christian. > > Fixes: 5fad79fd66ff ("drm/mm: cleanup and improve next_hole_*_addr()") > Signed-off-by: Jing Xiangfeng > --- > drivers/gpu/drm/drm_mm.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c > index a4a04d246135..6fcf70f71962 100644 > --- a/drivers/gpu/drm/drm_mm.c > +++ b/drivers/gpu/drm/drm_mm.c > @@ -392,11 +392,14 @@ first_hole(struct drm_mm *mm, > #define DECLARE_NEXT_HOLE_ADDR(name, first, last) \ > static struct drm_mm_node *name(struct drm_mm_node *entry, u64 size) \ > { \ > - struct rb_node *parent, *node = &entry->rb_hole_addr; \ > + struct rb_node *parent, *node; \ > \ > - if (!entry || RB_EMPTY_NODE(node)) \ > + if (!entry) \ > return NULL; \ > \ > + node = &entry->rb_hole_addr; \ > + if (RB_EMPTY_NODE(node)) \ > + return NULL; \ > if (usable_hole_addr(node->first, size)) { \ > node = node->first; \ > while (usable_hole_addr(node->last, size)) \