netdev - Re: [PATCH v2 net-next] ipv6: Add sanity checks on ipv6_devconf.seg6

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Message-ID: <ed08170f-4c9b-44df-9299-6bdec5aa5d38@6wind.com>
Date: Fri, 5 Sep 2025 10:12:45 +0200
From: Nicolas Dichtel <nicolas.dichtel@...nd.com>
To: Yue Haibing <yuehaibing@...wei.com>, davem@...emloft.net,
 dsahern@...nel.org, edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
 horms@...nel.org
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 net-next] ipv6: Add sanity checks on
 ipv6_devconf.seg6_enabled

Le 03/09/2025 à 13:56, Yue Haibing a écrit :
> In ipv6_srh_rcv() we use min(net->ipv6.devconf_all->seg6_enabled,
> idev->cnf.seg6_enabled) is intended to return 0 when either value is zero,
> but if one of the values is negative it will in fact return non-zero.
> 
> Signed-off-by: Yue Haibing <yuehaibing@...wei.com>
> ---
> v2: use proc_dointvec_minmax()
> ---
>  net/ipv6/addrconf.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> index 40e9c336f6c5..69ec9cb6031e 100644
> --- a/net/ipv6/addrconf.c
> +++ b/net/ipv6/addrconf.c
> @@ -7192,7 +7192,9 @@ static const struct ctl_table addrconf_sysctl[] = {
>  		.data		= &ipv6_devconf.seg6_enabled,
>  		.maxlen		= sizeof(int),
>  		.mode		= 0644,
> -		.proc_handler	= proc_dointvec,
> +		.proc_handler	= proc_dointvec_minmax,
> +		.extra1		= SYSCTL_ZERO,
> +		.extra2		= SYSCTL_ONE,
This sysctl has existed for almost a decade; you cannot change it, as it may
break a user setup that was using another value.

Regards,
Nicolas