Received-SPF: pass (google.com: domain of linux-wireless+bounces-414-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
Message-ID: <10737d34-0070-41f5-8903-dcae30ee7ba5@6wind.com>
Date: Tue, 5 Dec 2023 08:58:45 +0100
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Reply-To: nicolas.dichtel@6wind.com
Subject: Re: [PATCH v2] netlink: Return unsigned value for nla_len()
Content-Language: en-US
To: Kees Cook <keescook@chromium.org>
Cc: Jakub Kicinski <kuba@kernel.org>, kernel test robot <lkp@intel.com>,
 "David S. Miller" <davem@davemloft.net>, Eric Dumazet <edumazet@google.com>,
 Paolo Abeni <pabeni@redhat.com>, Johannes Berg <johannes@sipsolutions.net>,
 Jeff Johnson <quic_jjohnson@quicinc.com>, Michael Walle <mwalle@kernel.org>,
 Max Schulze <max.schulze@online.de>, netdev@vger.kernel.org,
 linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org,
 linux-hardening@vger.kernel.org
References: <20231202202539.it.704-kees@kernel.org>
 <95924d9e-b373-40fd-993c-25b0bae55e61@6wind.com>
 <202312041420.886C9F3@keescook>
From: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Organization: 6WIND
In-Reply-To: <202312041420.886C9F3@keescook>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Le 04/12/2023 à 23:21, Kees Cook a écrit :
[snip]
>>> diff --git a/include/uapi/linux/netlink.h b/include/uapi/linux/netlink.h
>>> index f87aaf28a649..270feed9fd63 100644
>>> --- a/include/uapi/linux/netlink.h
>>> +++ b/include/uapi/linux/netlink.h
>>> @@ -247,7 +247,7 @@ struct nlattr {
>>>  
>>>  #define NLA_ALIGNTO		4
>>>  #define NLA_ALIGN(len)		(((len) + NLA_ALIGNTO - 1) & ~(NLA_ALIGNTO - 1))
>>> -#define NLA_HDRLEN		((int) NLA_ALIGN(sizeof(struct nlattr)))
>>> +#define NLA_HDRLEN		((__u16) NLA_ALIGN(sizeof(struct nlattr)))
>> I wonder if this may break the compilation of some userspace tools with errors
>> like comparing signed and unsigned values.
> 
> Should I drop this part, then?
> 
Yes please.


Thank you,
Nicolas