Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1752912AbdFMJ33 (ORCPT <rfc822;w@1wt.eu>);
        Tue, 13 Jun 2017 05:29:29 -0400
Received: from mail-wr0-f193.google.com ([209.85.128.193]:33262 "EHLO
        mail-wr0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1751884AbdFMJ30 (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 13 Jun 2017 05:29:26 -0400
Subject: Re: [PATCH] fs: fcntl, avoid undefined behaviour
To: zhong jiang <zhongjiang@huawei.com>
Cc: viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org,
        Jeff Layton <jlayton@poochiereds.net>,
        "J. Bruce Fields" <bfields@fieldses.org>,
        linux-fsdevel@vger.kernel.org, Xishi Qiu <qiuxishi@huawei.com>
References: <20161014092342.25546-1-jslaby@suse.cz>
 <593E20A1.10608@huawei.com>
From: Jiri Slaby <jslaby@suse.cz>
Message-ID: <53f29baf-4da1-f2db-aec4-32291dc8db7d@suse.cz>
Date: Tue, 13 Jun 2017 11:29:23 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.1.1
MIME-Version: 1.0
In-Reply-To: <593E20A1.10608@huawei.com>
Content-Type: text/plain; charset=iso-8859-2
Content-Language: en-GB
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 1581
Lines: 52

On 06/12/2017, 07:03 AM, zhong jiang wrote:
> On 2016/10/14 17:23, Jiri Slaby wrote:
>> fcntl(0, F_SETOWN, 0x80000000) triggers:
>> UBSAN: Undefined behaviour in fs/fcntl.c:118:7
>> negation of -2147483648 cannot be represented in type 'int':
>> CPU: 1 PID: 18261 Comm: syz-executor Not tainted 4.8.1-0-syzkaller #1
>> ...
>> Call Trace:
>> ...
>>  [<ffffffffad8f0868>] ? f_setown+0x1d8/0x200
>>  [<ffffffffad8f19a9>] ? SyS_fcntl+0x999/0xf30
>>  [<ffffffffaed1fb00>] ? entry_SYSCALL_64_fastpath+0x23/0xc1
>>
>> Fix that by checking the arg parameter properly (against INT_MAX) and
>> return immediatelly in case it is wrong. No error is returned, the
>> same as in other cases.
>>
>> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
>> Cc: Jeff Layton <jlayton@poochiereds.net>
>> Cc: "J. Bruce Fields" <bfields@fieldses.org>
>> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
>> Cc: linux-fsdevel@vger.kernel.org
>> ---
>>  fs/fcntl.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/fs/fcntl.c b/fs/fcntl.c
>> index 350a2c8cfd28..bfc3b040d956 100644
>> --- a/fs/fcntl.c
>> +++ b/fs/fcntl.c
>> @@ -112,6 +112,10 @@ void f_setown(struct file *filp, unsigned long arg, int force)
>>  	enum pid_type type;
>>  	struct pid *pid;
>>  	int who = arg;
>> +
>> +	if (arg > INT_MAX)
>> +		return;
>> +
>>  	type = PIDTYPE_PID;
>>  	if (who < 0
>>  		type = PIDTYPE_PGID;
> Hi, Jiri
> 
> I hit the same issue,  but I see the upstream is still not changed.  Had any problem?

Hi, it needed an update which I have just sent. So let's see if that
gets applied.

thanks,
-- 
js
suse labs