linux-kernel - Re: [PATCH v2 4/5] ipc: Clamp msgmni and shmmni to the real IPCMNI limit

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Message-ID: <adeb1e42-6b59-bdcf-67f6-f8a9b6ae0742@redhat.com>
Date:   Wed, 28 Feb 2018 12:56:43 -0500
From:   Waiman Long <longman@...hat.com>
To:     "Luis R. Rodriguez" <mcgrof@...nel.org>
Cc:     Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH v2 4/5] ipc: Clamp msgmni and shmmni to the real IPCMNI
 limit

On 02/27/2018 08:01 PM, Luis R. Rodriguez wrote:
> On Tue, Feb 27, 2018 at 03:49:50PM -0500, Waiman Long wrote:
>> diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c
>> index 8ad93c2..e4ab272 100644
>> --- a/ipc/ipc_sysctl.c
>> +++ b/ipc/ipc_sysctl.c
>> @@ -41,12 +41,17 @@ static int proc_ipc_dointvec(struct ctl_table *table, int write,
>>  static int proc_ipc_dointvec_minmax(struct ctl_table *table, int write,
>>  	void __user *buffer, size_t *lenp, loff_t *ppos)
>>  {
>> +	int ret;
>>  	struct ctl_table ipc_table;
>>  
>>  	memcpy(&ipc_table, table, sizeof(ipc_table));
>>  	ipc_table.data = get_ipc(table);
>>  
>> -	return proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos);
>> +	ret = proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos);
>> +
>> +	table->flags |= ipc_table.flags; /* Copy back any change in flags */
> This seems fragile, why are we requiring this to be done by the users of
> CTL_FLAGS_CLAMP_RANGE ?
>
>   Luis

I should have just copied back the CTL_FLAGS_OOR_WARNED flag. That will
clarify what it is for.

Cheers,
Longman