Re: [PATCH net] ipvs: Improve robustness to the ipvs sysctl

[Florian Westphal <fw@strlen.de>]

hujunwei <hujunwei4@huawei.com> wrote:

[ trimmed CC list ]

> The ipvs module parse the user buffer and save it to sysctl,
> then check if the value is valid. invalid value occurs
> over a period of time.
> Here, I add a variable, struct ctl_table tmp, used to read
> the value from the user buffer, and save only when it is valid.

Does this cause any problems?  If so, what are those?

> Fixes: f73181c8288f ("ipvs: add support for sync threads")
> Signed-off-by: Junwei Hu <hujunwei4@huawei.com>
> ---
>  net/netfilter/ipvs/ip_vs_ctl.c | 61 +++++++++++++++++++++++-----------
>  1 file changed, 42 insertions(+), 19 deletions(-)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> index 741d91aa4a8d..e78fd05f108b 100644
> --- a/net/netfilter/ipvs/ip_vs_ctl.c
> +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> @@ -1680,12 +1680,18 @@ proc_do_defense_mode(struct ctl_table *table, int write,
>  	int val = *valp;
>  	int rc;
> 
> -	rc = proc_dointvec(table, write, buffer, lenp, ppos);
> +	struct ctl_table tmp = {
> +		.data = &val,
> +		.maxlen = sizeof(int),
> +		.mode = table->mode,
> +	};
> +
> +	rc = proc_dointvec(&tmp, write, buffer, lenp, ppos);

Wouldn't it be better do use proc_dointvec_minmax and set the
constraints via .extra1,2 in the sysctl knob definition?