Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
To:     Maximilian Heyne <mheyne@amazon.de>
Cc:     Kashyap Desai <kashyap.desai@broadcom.com>,
        Sumit Saxena <sumit.saxena@broadcom.com>,
        Shivasharan S <shivasharan.srikanteshwara@broadcom.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        James Bottomley <JBottomley@Parallels.com>,
        Adam Radford <aradford@gmail.com>,
        Christoph Hellwig <hch@infradead.org>,
        <megaraidlinux.pdl@broadcom.com>, <linux-scsi@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] scsi: megaraid: Fix uninitialized mbox in mega_cmd_done
From:   "Martin K. Petersen" <martin.petersen@oracle.com>
Organization: Oracle Corporation
Message-ID: <yq1v8g8b0e8.fsf@ca-mkp.ca.oracle.com>
References: <20230531133259.55619-1-mheyne@amazon.de>
Date:   Wed, 31 May 2023 18:38:12 -0400
In-Reply-To: <20230531133259.55619-1-mheyne@amazon.de> (Maximilian Heyne's
        message of "Wed, 31 May 2023 13:32:59 +0000")
Content-Type: text/plain
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?9kNFYuBzsybRp3UyB7HvzkLqmHde7c3NlchU9/ajtq0jNHnh5YtZdclaesFu?=
 =?us-ascii?Q?nZKkfMLUMS6tavPJFHTjqHWLgmyoHB61g+0Ir/CIrXXZqeEizkjl45lpHbHy?=
 =?us-ascii?Q?A9iWPAB450AXap1gIx/0ezCOnbNNwxi6gd/vL4RNHDkkinCpUX51szeI0DEV?=
 =?us-ascii?Q?i5OmHnEm9XGBxYHVWubDgpV4pbtrrwkMZQYr3B2PDTMrgwQUSv+cMcLfUPqp?=
 =?us-ascii?Q?ytyFAoIokxYzadESdjMmjTmowvRWz9jtQeOGr1iBGeJ1+0uqPca8wl1rQvl8?=
 =?us-ascii?Q?7l7THUvGA64jsh7Z3q0Mu2IHVoc2VPSvZYB9NdN6VYTU4du0h7Ogn/cX28dh?=
 =?us-ascii?Q?MRXICaII1f/XVIkjdDJuEoMZruwS78o/PM/6jVi5H1tcL/n9gep9Rx451Ke0?=
 =?us-ascii?Q?iGCj/QS1aEs825L81N8pMKHkDyrB5rD/g9dZ9k7hnI+3nW14qbNp7Kl7C9JO?=
 =?us-ascii?Q?6MbbxBaQqeP4QbK2qjP1SR48K8fAWfN/ENJ41cOBZaabnRbTrhjrLDDjTbvn?=
 =?us-ascii?Q?lMYaJH1DbOFb/ihCecHvWlFtN7gdKC7KTKJBnI7ZPJSRDhK3eLDBUp2Ob7x+?=
 =?us-ascii?Q?cHE5FAfnK2hqnPcMSpTawYosds+KJ0Iz9/0RF5qEN9y8M3EAkbkUfq0qPIL0?=
 =?us-ascii?Q?6Wd7+p0J3Y9pkFPcj3rqeOz8axEyMNYCsOqcMJyYvdNgbsU0nXYxqj6kQDay?=
 =?us-ascii?Q?0yS11klM40reaVCDKQZ80mboLX0UDc64eLCob9M1ewRXa7ndzd0EcwutAj3b?=
 =?us-ascii?Q?ew1RuOzj0/u1SbdSVs0zHQFoPhLPBQ2MyXl1/Vwi6N+xpfkddkcXDkE3tgsr?=
 =?us-ascii?Q?gtgE62yDhXrbVGVGn2aV3+PojB+66ZWISMONd73gTuJgGvQRxhNjr1VVvF7W?=
 =?us-ascii?Q?na9U6yORfi0mPNthCFeaZmJdL52wFP6KQD+aRJHiSApszX3xZ5NvPvwfmAwD?=
 =?us-ascii?Q?oUvU+8MWpTrrALDQbG291qheVw76cdqNcBbOEp0Msu0hPFfwFI1r+nNCOrUu?=
 =?us-ascii?Q?DK7/WrwINZdnWd2cvHawqI/4lmgrj6SeLv6+XTj1sDsrOaMcoNe5ZXzmRutd?=
 =?us-ascii?Q?qwF7mFmqPIqLCz0OI2ghaorFu9xQe2T1XK/Cebf0GBctT6JK8WsIJwaGiDoZ?=
 =?us-ascii?Q?Gzh/r0kfaiN0HpyJToBVFQBURi1Rbf9AT+oHYtNdLwzDUMRk0ac+Guj2IXGN?=
 =?us-ascii?Q?dCgilepcK37SjWeLN/nbIIFD8NKAIJ4iaxhNuDtKVk36u/UcxYx4swr8V2Fm?=
 =?us-ascii?Q?M1JBJGhs++C7pRS9U1NU7LV08ADT9w5QjA8S7Szq8q504uvZxWErjcuIKqRD?=
 =?us-ascii?Q?vGz1nTWaw1GGGzV7XeSSXuy63pIjverCjY7g0IsQU4rvQbEb3teHbjAqwVcJ?=
 =?us-ascii?Q?SnCNR0l8QfM/AnGTx5vvv4DkBSL2ZaHGDn+KsG8bqSeFGWvW7mecKlxGyRnv?=
 =?us-ascii?Q?oSfSa/PYDwgb5uHbaXjCWDebUXGp17elrUxmNcCZPxjpuZCI77Stj3A9BQpl?=
 =?us-ascii?Q?iIk/DxbYOJP/2E5NlodKpvPZprWpy7+/+99senPhDasxM4SdSF03VB6druyz?=
 =?us-ascii?Q?IoqEn7dB6xUD0LdqY6xRdddUdYGaabancCQ9WVAHuydqvGzQ1l3lcSA38Oq9?=
 =?us-ascii?Q?fQ=3D=3D?=
X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: =?us-ascii?Q?iQtCoEpUCCTcEV8HMmRyeuaEArseakud3oDt43y51TLFtGlJR9/jkC9nMX4A?=
 =?us-ascii?Q?eTlrYcmMtwmJdtozOtvsmfvUihYzJTwUkqPXu2q4RKWcTPBK2iQ3/VCAOfXx?=
 =?us-ascii?Q?4mtqmrcOK6Da3xCfacZAatu1mMGkt5IfbqCy9Xf9z+ES+AVwHyViWADtIdoW?=
 =?us-ascii?Q?7agiypzzq2DafA5BtRXBOUMvAPBQBlM/MyIWKjzWnbTJjOdJ7YIN2QBN+fNL?=
 =?us-ascii?Q?AjzjdDgNpiE1bGT9FhZGOJnWIl+D9Nbm3ECeUquWAkRMkV1GkksJrg6hgdDB?=
 =?us-ascii?Q?nCx4ddU66VbrmnvLvnrlUP0ulHcF5DEuUOHCN8taPvqDgfueJN5mtOwYJshy?=
 =?us-ascii?Q?EKEFQ3gBPfo1o2NP3Pk2wQl+OeLm7wSYexjjGJkhtopkks6FA3MYCqut+boE?=
 =?us-ascii?Q?1m7xqy1B07ghqv05uFRDnK1AwBeghvuykT6BWYajdieLRwb+Bhm2l0v5ZB/D?=
 =?us-ascii?Q?/kOwiuwD0j/+dQOqMCDr21PY1N651tMaXqSl8mnPYAraBSDJecckvUf08gh3?=
 =?us-ascii?Q?g1Xj6zWg1VmL7IlmBvpPk6k4fIw6Fuhi3Iyv6WJURAgxx8CZkw8HS8gVZtYf?=
 =?us-ascii?Q?v5pgfdOj9cg1hm5HczbqzP6v1k494P7OnDF89GkcUWpqYHJFTvxBErxd0Jks?=
 =?us-ascii?Q?HORnHWJbSlWPJHOcdrp9kZov2+lv+GB0uk6KPN7SY9bB1sb+z6hZKv2mqvpG?=
 =?us-ascii?Q?9f4IRb1++Wr1yERXeGWpJOsXidvfNnhvfvfat9t7jnczAslzkopGi0TJeF5E?=
 =?us-ascii?Q?OPsNFaruo80A6D8lJt/AuM1ZS4kEckLQKeIMlPhoi0WYDYb7adAHvvfFu4AE?=
 =?us-ascii?Q?bqDQ/U+2/VUKt/6a8Fz3p0f9+/FOXMHSSTXQAZLixCNFNf4ZPnE2xeOj55uP?=
 =?us-ascii?Q?/ydRqzwGi++5NNyR5PMTh2/TR/ow1tizYtopUJLU0ls4lJWFT79TsGeVwRCc?=
 =?us-ascii?Q?KX7p+x3BDgwr0KE1K/dpbQ=3D=3D?=
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 344f8fa5-0bca-4c54-f187-08db6227b92e
X-MS-Exchange-CrossTenant-AuthSource: PH0PR10MB4759.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 31 May 2023 22:38:15.5288
 (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: uqoX9QI/+QsAIjvWakpifVGc93aJOC7MKtRp4m7biWG2zLVF+SScrQIa4nJumeHM0wU84katkEUAH5sW91XHOBlWyf6RoGzbfZLYfiQD1Ac=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR10MB5853
X-Proofpoint-Virus-Version: vendor=baseguard
 engine=ICAP:2.0.254,Aquarius:18.0.957,Hydra:6.0.573,FMLib:17.11.176.26
 definitions=2023-05-31_16,2023-05-31_03,2023-05-22_02
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 adultscore=0 spamscore=0
 phishscore=0 malwarescore=0 mlxlogscore=999 mlxscore=0 bulkscore=0
 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2304280000
 definitions=main-2305310191
X-Proofpoint-GUID: tzNCpMhZYtXkK-HyhHnViwH0XQIc3WGQ
X-Proofpoint-ORIG-GUID: tzNCpMhZYtXkK-HyhHnViwH0XQIc3WGQ
X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,
        RCVD_IN_MSPIKE_H5,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE,
        T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org


Hi Maximilian!

> This is similar to commit 7a2ae008a53c ("scsi: megaraid: Fix
> mega_cmd_done() CMDID_INT_CMDS").

That's supposed to be commit 75cb113cd43f, right?

> When cmdid == CMDID_INT_CMDS and status != 0 then mbox is still NULL
> but is dereferenced below.

Is this actually a valid scenario, though? The mbox is only dereferenced
if there is status returned from an attached device. And I am guessing
that a controller-internal command does not talk to any attached device.
Thus status should always be 0 for CMDID_INT_CMDS. I don't have the
megaraid firmware manual so this is pure guesswork on my part. But you
would think we would have come across an invalid deref since the
original 2014 commit made the offending change.

-- 
Martin K. Petersen	Oracle Linux Engineering