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Tue, 12 Oct 2021 15:12:37 +0000 Date: Tue, 12 Oct 2021 18:12:18 +0300 From: Dan Carpenter To: Thomas =?iso-8859-1?Q?Hellstr=F6m?= Cc: Colin King , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , David Airlie , Daniel Vetter , Matthew Auld , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH][next] drm/i915: Fix dereference of pointer backup before it is null checked Message-ID: <20211012151218.GF8429@kadam> References: <20211012132549.260089-1-colin.king@canonical.com> Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-ClientProxiedBy: JN2P275CA0046.ZAFP275.PROD.OUTLOOK.COM (2603:1086:0:2::34) To MWHPR1001MB2365.namprd10.prod.outlook.com (2603:10b6:301:2d::28) MIME-Version: 1.0 Received: from kadam (62.8.83.99) by JN2P275CA0046.ZAFP275.PROD.OUTLOOK.COM (2603:1086:0:2::34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4587.21 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?iso-8859-1?Q?AGUB5G3UWS5e5Iw1tbZAyX7KjMypYWmgibhW9doarpFjSXvvRMriTvYTrE?= =?iso-8859-1?Q?w5ntB0Yi7Z8BuyAFCTQlH6DiEBNZk760dMqWCR5TRV2Om0vnpR1Tzp7K7O?= =?iso-8859-1?Q?1cqSNNOsP/2rlG5ias6/h6SYh6A6kIJKaE9sT+6zl0VgL1POkM+ZE6WLX1?= =?iso-8859-1?Q?NyXmRzCxzJTzWF7lxaTS6ZCReE3hoZGkNqVULafW/HmGivdMJ/7Ulgn5uN?= =?iso-8859-1?Q?vrT+Mkf9qaU7Lhsw6H1imqCVLElVVMPbaN5+rEUMWbq+NMRN5tPLbepYNB?= =?iso-8859-1?Q?OkiXtSUhgO9k+1gfmHw3TKdayZHwo/0WZMsV09pBCtrJdNL1smpZ+WhGgx?= =?iso-8859-1?Q?R6f0T8+Geuex7uNBGITZR7lnlNrhtwOAPD3XCe4PcjbsN+vrALa50WqONq?= =?iso-8859-1?Q?15TgbusV53BHnFkoWYwdvrLRheK8f6t4VMnWGCqOA3YYg0dwZmEtoJrPhR?= =?iso-8859-1?Q?myZb2V99HlR+fn6DeRCV5FdNvZxhxu6kl8BZy0r9Ltn+/LeGrcxQZdKv+P?= =?iso-8859-1?Q?wlTAPPl/HLmoKeiTm31cVrqWvAnox8HFY++EHrMMA/f3Y+QH/Uqm+HOTpH?= =?iso-8859-1?Q?zPySmuOJSZmBoHZyNtBlaOwT9Ht/zoaHhcqW27HmTTHQ//jzDOSUfR5OW9?= =?iso-8859-1?Q?GSGy1LiLrIr2gBOcBjSY6GMF3dH40Y757USiJB4D1sSAIEDX9eErKSfwtI?= =?iso-8859-1?Q?PEQGfkhOo1340/9RuN2CtZ2w1be9ZyjHvZCQBMc2VQkx7E36QazYgHZ1NA?= =?iso-8859-1?Q?JAV2REuU6vaxkBXTHIgtCBrDgz49USHz2FkxO30GSiqnCFsRyb5sabSqqG?= =?iso-8859-1?Q?GfFXBkgZZ0harzIxvfbYvPTMPqp10gfly/6HK7HJYBjjTByWqkSf/tNWAf?= =?iso-8859-1?Q?xsRwIsqQNPIh3OFHoshNIw69rnll1Vy0bJyVZrEu/mZHqV7WyaFbd/34PI?= =?iso-8859-1?Q?BQANfL5eyqoSIwjAjG9pQKreCkQQ6ucS8raOqJxSdO2838Pk3vQ3wSrwwu?= =?iso-8859-1?Q?F+CH4cjLPCAq1eHo41ZX4yBxEZPL0mTyo17BZRZ1c9qvo+097yDeq8lxQk?= =?iso-8859-1?Q?fYIdNyTi7uRIOvBBw65ul7N3UkGLFWNA4CU6/eumk2Q1zjBV+YbrVZBgKH?= =?iso-8859-1?Q?e1rVGOKXVDW5yrmNoICZFXIii9R9t4hFHK1QQDN0Lh8zNhpAK/FqRT5kXs?= =?iso-8859-1?Q?wdJALj7mwcV7Y78P4ROqFwc1ezE5gg/D2e6osSqxVcqCkezjo9Kq9ELWpw?= =?iso-8859-1?Q?/eaYEdOf745S7vj+GAzyqcRDdzk2d6mEkC+MGIR34ttJ1IaSOK+IJoYicD?= =?iso-8859-1?Q?/ALz2tQz/GXzSemayNS4gtAS7+2A322HTS91rOZ9I2f4WRF4M/Nn48liBl?= =?iso-8859-1?Q?LJAgRQu+Ty?= X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-Network-Message-Id: a9698186-5dd2-4c61-3c62-08d98d92b96a X-MS-Exchange-CrossTenant-AuthSource: MWHPR1001MB2365.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 12 Oct 2021 15:12:37.2050 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: EFkHbay6bmjbnKeZJkrXwHxePsz3PKtpeufa/0sFhQJ4J9fDJfEB5QMbbZ80WLhDpgnnF5gFO4x8gcGHsJynRDeKDWAky7Oo0r2sjFyyK7A= X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW5PR10MB5808 X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10135 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 phishscore=0 suspectscore=0 mlxlogscore=999 mlxscore=0 bulkscore=0 adultscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2109230001 definitions=main-2110120085 X-Proofpoint-ORIG-GUID: 8ITYZy3AUPlyLj8yqPfoLZRWgpqth-CX X-Proofpoint-GUID: 8ITYZy3AUPlyLj8yqPfoLZRWgpqth-CX Precedence: bulk List-ID: X-Mailing-List: kernel-janitors@vger.kernel.org On Tue, Oct 12, 2021 at 04:47:24PM +0200, Thomas Hellström wrote: > Hi, > > On 10/12/21 15:25, Colin King wrote: > > From: Colin Ian King > > > > The assignment of pointer backup_bo dereferences pointer backup before > > backup is null checked, this could lead to a null pointer dereference > > issue. Fix this by only assigning backup_bo after backup has been null > > checked. > > > > Addresses-Coverity: ("Dereference before null check") > > Fixes: c56ce9565374 ("drm/i915 Implement LMEM backup and restore for suspend / resume") > > Signed-off-by: Colin Ian King > > There's not really a pointer dereference here, just pointer arithmetics, so > the code should be safe (but admittedly fragile), so to keep Coverity happy, > > Reviewed-by: Thomas Hellström Yeah. I kind of feel like we shouldn't work around static checker bugs. But when we do then there shouldn't be a Fixes tag. regards, dan carpenter