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SubjectRe: [PATCH] proc/sysctl: fix return error for proc_doulongvec_minmax
On Thu, Dec 06, 2018 at 03:36:15PM +0800, Cheng Lin wrote:
> If the number of input parameters is less than the total
> parameters, an EINVAL error will be returned.
>
> e.g.
> We use proc_doulongvec_minmax to pass up to two parameters
> with kern_table.
>
> {
> .procname = "monitor_signals",
> .data = &monitor_sigs,
> .maxlen = 2*sizeof(unsigned long),
> .mode = 0644,
> .proc_handler = proc_doulongvec_minmax,
> },
>
> Reproduce:
> When passing two parameters, it's work normal. But passing
> only one parameter, an error "Invalid argument"(EINVAL) is
> returned.
>
> [root@cl150 ~]# echo 1 2 > /proc/sys/kernel/monitor_signals
> [root@cl150 ~]# cat /proc/sys/kernel/monitor_signals
> 1 2
> [root@cl150 ~]# echo 3 > /proc/sys/kernel/monitor_signals
> -bash: echo: write error: Invalid argument
> [root@cl150 ~]# echo $?
> 1
> [root@cl150 ~]# cat /proc/sys/kernel/monitor_signals
> 3 2
> [root@cl150 ~]#
>
> The following is the result after apply this patch. No error
> is returned when the number of input parameters is less than
> the total parameters.
>
> [root@cl150 ~]# echo 1 2 > /proc/sys/kernel/monitor_signals
> [root@cl150 ~]# cat /proc/sys/kernel/monitor_signals
> 1 2
> [root@cl150 ~]# echo 3 > /proc/sys/kernel/monitor_signals
> [root@cl150 ~]# echo $?
> 0
> [root@cl150 ~]# cat /proc/sys/kernel/monitor_signals
> 3 2
> [root@cl150 ~]#
>
> There are three processing functions dealing with digital parameters,
> __do_proc_dointvec/__do_proc_douintvec/__do_proc_doulongvec_minmax.
>
> This patch deals with __do_proc_doulongvec_minmax, just as
> __do_proc_dointvec does, adding a check for parameters 'left'. In
> __do_proc_douintvec, its code implementation explicitly does not
> support multiple inputs.
>
> static int __do_proc_douintvec(...){
> ...
> /*
> * Arrays are not supported, keep this simple. *Do not* add
> * support for them.
> */
> if (vleft != 1) {
> *lenp = 0;
> return -EINVAL;
> }
> ...
> }
>
> So, just __do_proc_doulongvec_minmax has the problem. And most use of
> proc_doulongvec_minmax/proc_doulongvec_ms_jiffies_minmax just have one
> parameter.
>
> Signed-off-by: Cheng Lin <cheng.lin130@zte.com.cn>

Thanks for fixing up the commit log.

Acked-by: Luis Chamberlain <mcgrof@kernel.org>

I think we can live with this outside of stable. So stable is not
needed. But I would not be surprised if autosel algorithm will end
up picking it up. And if so.. well, it cannot hurt.

Luis

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