netdev - Re: [net-next V6 PATCH 1/5] bpf: introduce new bpf cpu map type BPF_MAP_TYPE

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Date:   Wed, 11 Oct 2017 07:36:28 +0200
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     netdev@...r.kernel.org, jakub.kicinski@...ronome.com,
        "Michael S. Tsirkin" <mst@...hat.com>, pavel.odintsov@...il.com,
        Jason Wang <jasowang@...hat.com>, mchan@...adcom.com,
        John Fastabend <john.fastabend@...il.com>,
        peter.waskiewicz.jr@...el.com,
        Daniel Borkmann <borkmann@...earbox.net>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Andy Gospodarek <andy@...yhouse.net>, brouer@...hat.com
Subject: Re: [net-next V6 PATCH 1/5] bpf: introduce new bpf cpu map type
 BPF_MAP_TYPE_CPUMAP

On Wed, 11 Oct 2017 00:48:40 +0200
Daniel Borkmann <daniel@...earbox.net> wrote:

> On 10/10/2017 02:47 PM, Jesper Dangaard Brouer wrote:
> [...]
> > +static struct bpf_map *cpu_map_alloc(union bpf_attr *attr)
> > +{
> > +	struct bpf_cpu_map *cmap;
> > +	int err = -ENOMEM;
> > +	u64 cost;
> > +	int ret;
> > +
> > +	if (!capable(CAP_SYS_ADMIN))
> > +		return ERR_PTR(-EPERM);
> > +
> > +	/* check sanity of attributes */
> > +	if (attr->max_entries == 0 || attr->key_size != 4 ||
> > +	    attr->value_size != 4 || attr->map_flags & ~BPF_F_NUMA_NODE)
> > +		return ERR_PTR(-EINVAL);
> > +
> > +	cmap = kzalloc(sizeof(*cmap), GFP_USER);
> > +	if (!cmap)
> > +		return ERR_PTR(-ENOMEM);
> > +
> > +	/* mandatory map attributes */
> > +	cmap->map.map_type = attr->map_type;
> > +	cmap->map.key_size = attr->key_size;
> > +	cmap->map.value_size = attr->value_size;
> > +	cmap->map.max_entries = attr->max_entries;
> > +	cmap->map.map_flags = attr->map_flags;
> > +	cmap->map.numa_node = bpf_map_attr_numa_node(attr);
> > +
> > +	/* Pre-limit array size based on NR_CPUS, not final CPU check */
> > +	if (cmap->map.max_entries > NR_CPUS)
> > +		return ERR_PTR(-E2BIG);  
> 
> We still have a leak here, meaning kfree(cmap) is missing on above error.

Darn... yes, I introduced this in this V6 as I moved the check.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer