Date:   Fri, 17 Dec 2021 09:40:03 +0300
From:   Dan Carpenter <dan.carpenter@oracle.com>
To:     Alyssa Rosenzweig <alyssa@collabora.com>
Cc:     Steven Price <steven.price@arm.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        David Airlie <airlied@linux.ie>, Rob Herring <robh@kernel.org>,
        Tomeu Vizoso <tomeu.vizoso@collabora.com>,
        Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>,
        Boris Brezillon <boris.brezillon@collabora.com>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drm/panfrost: Avoid user size passed to kvmalloc()
Message-ID: <20211217064003.GF1978@kadam>
References: <20211216161603.983711-1-steven.price@arm.com>
 <Ybt8QWEAooP++R7a@maud>
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <Ybt8QWEAooP++R7a@maud>
User-Agent: Mutt/1.9.4 (2018-02-28)
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?o7AbvvgPj6105q51haBZB7ymQJBW3rdwl3pFFFt3twBVRC2ymdyyD32tcqmY?=
 =?us-ascii?Q?o3LxNkiJaYg6v/a+Z0i/IU11/hiJVljGEp+zg0lEngajxQY8pJoTQ3m7z7Wj?=
 =?us-ascii?Q?ZyzMyqv/eZI4U/ksxNzpc0mhbc0M5noNPqucY2/KNySe0nB1mF1pAhJ8zq/H?=
 =?us-ascii?Q?PbF+Jw8GqtWvkI6ZJRZvU94BFp5Tj2fXhvEq4YvSVyfWskZh07FwOJ1tjwh3?=
 =?us-ascii?Q?WfG/Me+zh0f3rgqOhQOSzpGvfkcFatZfhSnS76+KI0ZQVT8i/2khlQ53ezdm?=
 =?us-ascii?Q?Xfsg90vFs0uAIizwiRr7gFvjN/H9Ko9k9hjiJ8ZTmMNntC+LAT8ua8rUuqgj?=
 =?us-ascii?Q?4w3q0hzF049Au6eA0oOhqKk6rsucawQQDufE+cksgGQd7MPEQ1GbsokItRzu?=
 =?us-ascii?Q?RwSFH/s9kMR+urKu8n+nLDFHuw4V4kf0B7ppFoH8AirQPUy7+5Qpw/RG9fVE?=
 =?us-ascii?Q?3jwvMyVjAscvJkG5u+CuA2VPWCnyjS1qVMGkwswStzO2Sc6SLz3jdEaDZWt2?=
 =?us-ascii?Q?qYXyuH5H2BzkvhuCIrjfCLiekksz15eO9QcZGokthPrMkSHYXLET8pCPs2qp?=
 =?us-ascii?Q?4ngeC2fZl9Hm3EPQWVfRVhst9ITC7G8Tdd0hDOXaoedbMW6K4tr5LUHPpAvi?=
 =?us-ascii?Q?G/7AwMtTiT0sqTcL2RYvSHc1LMY9QmeGN/6MQli73P0KWSIgjOtgaWTB5oLi?=
 =?us-ascii?Q?hFAZPk5EX1+ZNoKPT+dExlnzxOVWrE+0Fq+BwL29TsjBuge/dxf/c4nrG9YJ?=
 =?us-ascii?Q?9Mj4VyaFh7Udfhgz8XU7Y74EMIK9cRJfFFn5f8z2GPREWI/g6rtWnnTloQN4?=
 =?us-ascii?Q?9iw4z9ZlP4BcQWu3pS+BUCMm0ckcggyZrR37N7+vBS9jwnXlWMQzpkJ7fmDa?=
 =?us-ascii?Q?lm5b4zQLD6L7A9BnlT+tikbAMZHIV+vrr5/ZUsd6++z7+mqm4jBdnMubBmPK?=
 =?us-ascii?Q?uQLy9mxb+FecML6C353lX5nI1whVI4X9yrRYR/of1+Z/lMagPgL5lagejQQS?=
 =?us-ascii?Q?Wtu1gr8iwOx5fu1Nu5qQD/YArOro/VBpgOspMJgr80rpgOJNa/fev4+4ff/t?=
 =?us-ascii?Q?WKgSFSFnIFh8AlKds31YN93iNu8KvJezudeyua7z5+CEDp/b8JaE/ru5R6xO?=
 =?us-ascii?Q?Q2MaZYMQIyrnre1Prlh3s8PvPsNBUBGqNURidpq7B6kpd8xK/3ch8T80SeGJ?=
 =?us-ascii?Q?xEhBIpyFCR5qUwC51J/M0Bw6Fo9s0cThNELEP79UBZQEpbrCmQ4Rx2rF7PQu?=
 =?us-ascii?Q?0nDiTYtTwo2so4LgjSsxUuFKRHTZTpO3O+JyY/7NqWXRaSDjSgcWJMyQOfK4?=
 =?us-ascii?Q?4LJEJ/yAAz0pHodUH7i+Qor7wUo9uGL9isJdcRQxrUxTaqeFviTcbPp59HS5?=
 =?us-ascii?Q?i7iMRngwLVLHw7H+qca9CFNK4oAjCtvV23cWKYa3l6MJUsKyr+kk2BzOOhVq?=
 =?us-ascii?Q?FFDqEr+gsheUX0fk3b0bVhl0XjRy6RkJ8GGIAGx7u8iSw+hr/DftYwO18qDp?=
 =?us-ascii?Q?Q20IDq+1qYoDeMXZpIfBCEZNrY9emtyYAO+fx/J//flUFp1bv6IZIPTkyEdh?=
 =?us-ascii?Q?6jw+8bWh8Cqs8tJ+UBHNF85AnCD0AorQ2sw6AthikxVQmOofd0agDZdVlL8q?=
 =?us-ascii?Q?Kxc8akMCcztLcg5niXhrALZ4gWUlVSxQVOeiJ+02o8G/aslkUHnXRibNcxt1?=
 =?us-ascii?Q?6+fvZnElKFYFoRPaXzWAWxMAcfc=3D?=
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 9e036093-b7fb-44b0-c337-08d9c1281ca7
X-MS-Exchange-CrossTenant-AuthSource: MWHPR1001MB2365.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 17 Dec 2021 06:40:27.4904
 (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: pEiF0j263PRj3ekUtFXrVTnSMw1fjrhrCnfXGki33ze3hmsLd84a+Txi0TGHoGv04iPzHnkjqOhyGkTE0v0SAnsV2KkrRtGCJlaPeO5gYU8=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR1001MB2365
X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10200 signatures=668683
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 phishscore=0
 spamscore=0 mlxscore=0 adultscore=0 bulkscore=0 suspectscore=0
 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1
 engine=8.12.0-2110150000 definitions=main-2112170037
X-Proofpoint-ORIG-GUID: gjbsAWbxpcJIgm1ji7jdZVfkhyeJf8JQ
X-Proofpoint-GUID: gjbsAWbxpcJIgm1ji7jdZVfkhyeJf8JQ
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, Dec 16, 2021 at 12:49:53PM -0500, Alyssa Rosenzweig wrote:
> > This provides an easy method for user
> > space to trigger the OOM killer (by temporarily allocating large amounts
> > of kernel memory)
> 
> panfrost user space has a lot of easy ways to trigger to the OOM killer
> unfortunately .... if this is something we want to fix there are a lot
> more patches coming :(

My static checker is only looking at the new rule that kvmalloc() can't
allocate more than 2GB.  But eventually syzbot will figure out how to
trigger the other OOMs so fixing that is going to be a requirement at
some point.

regards,
dan carpenter