Re: [PATCH v5] memcg: event control at vmpressure.

[Michal Hocko <mhocko@suse.cz>]

On Thu 20-06-13 11:17:39, Hyunhee Kim wrote:
[...]
> diff --git a/mm/vmpressure.c b/mm/vmpressure.c
> index 736a601..3c37b12 100644
> --- a/mm/vmpressure.c
> +++ b/mm/vmpressure.c
[...]
> @@ -303,10 +310,19 @@ int vmpressure_register_event(struct cgroup *cg, struct cftype *cft,
>  {
>  	struct vmpressure *vmpr = cg_to_vmpressure(cg);
>  	struct vmpressure_event *ev;
> +	char *strlevel = NULL, *strtrigger = NULL;

No need for initialization to NULL when both would be initialized below.

>  	int level;
>  
> +	strlevel = args;
> +	strtrigger = strchr(args, ' ');
> +
> +	if (strtrigger) {
> +		*strtrigger = '\0';
> +		strtrigger++;
> +	}
> +
>  	for (level = 0; level < VMPRESSURE_NUM_LEVELS; level++) {
> -		if (!strcmp(vmpressure_str_levels[level], args))
> +		if (!strcmp(vmpressure_str_levels[level], strlevel))
>  			break;
>  	}
>  
> @@ -319,6 +335,16 @@ int vmpressure_register_event(struct cgroup *cg, struct cftype *cft,
>  
>  	ev->efd = eventfd;
>  	ev->level = level;
> +	ev->last_level = -1;
> +
> +	if (strtrigger == NULL)
> +		ev->edge_trigger = false;
> +	else if (!strcmp(strtrigger, "always"))
> +		ev->edge_trigger = false;
> +	else if (!strcmp(strtrigger, "edge"))
> +		ev->edge_trigger = true;
> +	else
> +		return -EINVAL;

I have missed this before but this will cause a memory leak and worse it
is user controlled mem leak. Move this up after the level check.

>  	mutex_lock(&vmpr->events_lock);
>  	list_add(&ev->node, &vmpr->events);
> -- 
> 1.7.9.5
> 
> 
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-- 
Michal Hocko
SUSE Labs

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