linux-kernel - Re: [PATCH 02/24] bpfilter: fix up a sparse annotation

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Message-ID: <20200721024016.2talwdt5hjqvirr6@ltop.local>
Date:   Tue, 21 Jul 2020 04:40:16 +0200
From:   Luc Van Oostenryck <luc.vanoostenryck@...il.com>
To:     Christoph Hellwig <hch@....de>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Eric Dumazet <edumazet@...gle.com>,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        netfilter-devel@...r.kernel.org, coreteam@...filter.org,
        linux-sctp@...r.kernel.org, linux-hams@...r.kernel.org,
        linux-bluetooth@...r.kernel.org, bridge@...ts.linux-foundation.org,
        linux-can@...r.kernel.org, dccp@...r.kernel.org,
        linux-decnet-user@...ts.sourceforge.net,
        linux-wpan@...r.kernel.org, linux-s390@...r.kernel.org,
        mptcp@...ts.01.org, lvs-devel@...r.kernel.org,
        rds-devel@....oracle.com, linux-afs@...ts.infradead.org,
        tipc-discussion@...ts.sourceforge.net, linux-x25@...r.kernel.org
Subject: Re: [PATCH 02/24] bpfilter: fix up a sparse annotation

On Mon, Jul 20, 2020 at 02:47:15PM +0200, Christoph Hellwig wrote:
> The __user doesn't make sense when casting to an integer type.
> 
> Signed-off-by: Christoph Hellwig <hch@....de>
> ---
>  net/bpfilter/bpfilter_kern.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/bpfilter/bpfilter_kern.c b/net/bpfilter/bpfilter_kern.c
> index 977e9dad72ca4f..713b4b3d02005d 100644
> --- a/net/bpfilter/bpfilter_kern.c
> +++ b/net/bpfilter/bpfilter_kern.c
> @@ -49,7 +49,7 @@ static int __bpfilter_process_sockopt(struct sock *sk, int optname,
>  	req.is_set = is_set;
>  	req.pid = current->pid;
>  	req.cmd = optname;
> -	req.addr = (long __force __user)optval;
> +	req.addr = (__force long)optval;

For casts to integers, even '__force' is not needed (since integers
can't be dereferenced, the concept of address-space is meaningless
for them, so it's never useful to warn when it's dropped and
'__force' is thus not needed).

-- Luc