linux-kernel - Re: [PATCH v2 2/6] sysctl: Fixes nsm_local

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Message-ID: <ac5742e1-7a2b-4d74-889c-0a0c434c16e5@clip-os.org>
Date: Tue, 25 Feb 2025 11:37:57 +0100
From: Nicolas Bouchinet <nicolas.bouchinet@...p-os.org>
To: Chuck Lever <chuck.lever@...cle.com>, linux-kernel@...r.kernel.org,
 linux-rdma@...r.kernel.org, linux-scsi@...r.kernel.org,
 codalist@...a.cs.cmu.edu, linux-nfs@...r.kernel.org
Cc: Nicolas Bouchinet <nicolas.bouchinet@....gouv.fr>,
 Joel Granados <j.granados@...sung.com>, Clemens Ladisch
 <clemens@...isch.de>, Arnd Bergmann <arnd@...db.de>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Jason Gunthorpe <jgg@...pe.ca>, Leon Romanovsky <leon@...nel.org>,
 "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
 "Martin K. Petersen" <martin.petersen@...cle.com>,
 Jan Harkes <jaharkes@...cmu.edu>, Jeff Layton <jlayton@...nel.org>,
 Neil Brown <neilb@...e.de>, Olga Kornievskaia <okorniev@...hat.com>,
 Dai Ngo <Dai.Ngo@...cle.com>, Tom Talpey <tom@...pey.com>,
 Trond Myklebust <trondmy@...nel.org>, Anna Schumaker <anna@...nel.org>,
 Bart Van Assche <bvanassche@....org>, Zhu Yanjun <yanjun.zhu@...ux.dev>,
 Al Viro <viro@...iv.linux.org.uk>, Christian Brauner <brauner@...nel.org>
Subject: Re: [PATCH v2 2/6] sysctl: Fixes nsm_local_state bounds

On 2/24/25 15:38, Chuck Lever wrote:
> On 2/24/25 4:58 AM, nicolas.bouchinet@...p-os.org wrote:
>> From: Nicolas Bouchinet <nicolas.bouchinet@....gouv.fr>
>>
>> Bound nsm_local_state sysctl writings between SYSCTL_ZERO
>> and SYSCTL_INT_MAX.
>>
>> The proc_handler has thus been updated to proc_dointvec_minmax.
>>
>> Signed-off-by: Nicolas Bouchinet <nicolas.bouchinet@....gouv.fr>
>> ---
>>   fs/lockd/svc.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
>> index 2c8eedc6c2cc9..984ab233af8b6 100644
>> --- a/fs/lockd/svc.c
>> +++ b/fs/lockd/svc.c
>> @@ -461,7 +461,9 @@ static const struct ctl_table nlm_sysctls[] = {
>>   		.data		= &nsm_local_state,
>>   		.maxlen		= sizeof(int),
>>   		.mode		= 0644,
>> -		.proc_handler	= proc_dointvec,
>> +		.proc_handler	= proc_dointvec_minmax,
>> +		.extra1		= SYSCTL_ZERO,
>> +		.extra2		= SYSCTL_INT_MAX,
>>   	},
>>   };
>>   
> Hi Nicolas -
>
> nsm_local_state is an unsigned 32-bit integer. The type of that value is
> defined by spec, because this value is exchanged between peers on the
> network.
>
> Perhaps this patch should replace proc_dointvec with proc_douintvec
> instead.
>
>

Hi Chuck,

Thank's for your review.

If `nsm_local_state` should be set to the
full range of an uint32_t by a user writing in the sysctl, then yes it 
should
use `proc_douintvec` instead of limiting it to SYSCTL_INT_MAX value 
(INT_MAX).

I've used `proc_dointvec_minmax` since it already used `proc_dointvec` 
and thus
was already capped at INT_MAX.

Best regards,

Nicolas