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] userfaultfd: avoid the duplicated release for
 userfaultfd_ctx
From:   "Xu, Yanfei" <yanfei.xu@windriver.com>
To:     linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        Alexander Viro <viro@zeniv.linux.org.uk>
References: <20200714161203.31879-1-yanfei.xu@windriver.com>
Message-ID: <1a463530-107d-0893-cecf-87ba42ebdbf6@windriver.com>
Date:   Wed, 15 Jul 2020 09:41:29 +0800
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.7.0
In-Reply-To: <20200714161203.31879-1-yanfei.xu@windriver.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
X-MS-Exchange-MessageSentRepresentingType: 1
Received: from [128.224.162.160] (60.247.85.82) by HK0PR01CA0061.apcprd01.prod.exchangelabs.com (2603:1096:203:a6::25) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3195.18 via Frontend Transport; Wed, 15 Jul 2020 01:41:34 +0000
X-Originating-IP: [60.247.85.82]
X-MS-PublicTrafficType: Email
X-MS-Office365-Filtering-Correlation-Id: 510f572b-e05d-429e-1264-08d8286035a3
X-MS-TrafficTypeDiagnostic: BY5PR11MB4354:
X-Microsoft-Antispam-PRVS: <BY5PR11MB43540644F7FF9FCC73AED03EE47E0@BY5PR11MB4354.namprd11.prod.outlook.com>
X-MS-Oob-TLC-OOBClassifiers: OLM:669;
X-MS-Exchange-SenderADCheck: 1
X-Microsoft-Antispam: BCL:0;
X-Microsoft-Antispam-Message-Info: dtaNFx4No/wrumYvmGuGycGz8urjr4aUnW43NUZF5uc3kolJg/0F5L/CFW7oy+G6vp0YiVG0DevaVEy4ZpJ1XFfQW8pAKqSmNSe2QbkuY41F2WaIKCq5jsGtcfYu3IQpA5i4AX/9oSgwVcLjyOzQx/cVRcBkpesiWFzQWEYFGd4l3VoY3bS9qtTNVeA2+Nw62lXq9F6RgJhEcAuaPfEX1YyufBD2x0S5kWX1M0lHNwufK8+OiXytuNqsCuUPUA4m8QZOs6P62Z3QQTdcg/qUzlpbAhjc4szdwiSAg8nhhlpHg8HYRUeWscWuCWaFD5exd2zXmHDVrW0L71remr4rthmGsKGy+WYzSJyIGqy8hlLURnISTHkBezvELpaQBHU9RJOtRQJqpxNE3ceFDCNDQwOQw+yFzpsrm7+n5HxVq2TiiWg2KDmcFcU4Y32gmeM7
X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BY5PR11MB4241.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFTY:;SFS:(366004)(376002)(39850400004)(396003)(136003)(346002)(478600001)(2616005)(186003)(4744005)(26005)(66946007)(8676002)(16526019)(31696002)(86362001)(6916009)(66476007)(66556008)(5660300002)(6666004)(6706004)(956004)(16576012)(8936002)(52116002)(83380400001)(31686004)(2906002)(6486002)(316002)(36756003)(53546011)(78286006)(43740500002);DIR:OUT;SFP:1101;
X-MS-Exchange-AntiSpam-MessageData: e8id6lOHyuIevEHX17jr3C4OqsorjEUUc60wy9rveZGAup3V1MYUC1K+kCUwjzmEB+8TcplRQ51eZh1NVcR7MepoOsG2qOdj8zIDd1hRS2L7xkIwqap5LFS6ktMkDo3z/eifwbTntc7hboje8yBUaRsRqrvo02w8N2y0jcalfbLJ2mWqwnQl8xO6p2qCUqEiiHOv9I2BuAVJcGp7LjD/NQyxJbCO9mGhKkNxi2U6sY/VMCWIP5Xbro/0iKiiH8Ei4RFvVQUbhD/TbpgfqxiGm1rOudnm7fQqWNd63Z01WP7HWhdMEUnkKlNsIVjENO2KZu7UsTS177ZpMncx9nGgkI8Mqh5rw2jaTQHN1wUZQjw+orYFByIa4mRUwEkn6R3Anl61zdznfU5iV1VVMaSYaXzGYmwRwrqmfkOPDlHdgSz71g83qW6vwpDDCbZaYHBmIk1c307bqGF5gxvniG33w2uhKgybaSHphrHp3QgSKuY=
X-OriginatorOrg: windriver.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 510f572b-e05d-429e-1264-08d8286035a3
X-MS-Exchange-CrossTenant-AuthSource: BY5PR11MB4241.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Jul 2020 01:41:35.6665
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 8ddb2873-a1ad-4a18-ae4e-4644631433be
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: R98yxmSfP0IqATewOJr92InTDYOmxO1MMk6wDaXlv+9o0pTfQvRrxTtPY4V0RvH4g61IW969w3Jb1qEmIpNKQg==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR11MB4354
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Add maintainer Alexander Viro  :)

On 7/15/20 12:12 AM, yanfei.xu@windriver.com wrote:
> From: Yanfei Xu <yanfei.xu@windriver.com>
> 
> when get_unused_fd_flags gets failure, userfaultfd_ctx_cachep will
> be freed by userfaultfd_fops's release function which is the
> userfaultfd_release. So we could return directly after fput().
> 
> userfaultfd_release()->userfaultfd_ctx_put(ctx)
> 
> Fixes: d08ac70b1e0d (Wire UFFD up to SELinux)
> Reported-by: syzbot+75867c44841cb6373570@syzkaller.appspotmail.com
> Signed-off-by: Yanfei Xu <yanfei.xu@windriver.com>
> ---
>   fs/userfaultfd.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
> index 3a4d6ac5a81a..e98317c15530 100644
> --- a/fs/userfaultfd.c
> +++ b/fs/userfaultfd.c
> @@ -2049,7 +2049,7 @@ SYSCALL_DEFINE1(userfaultfd, int, flags)
>   	fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
>   	if (fd < 0) {
>   		fput(file);
> -		goto out;
> +		return fd;
>   	}
>   
>   	ctx->owner = file_inode(file);
>