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

Jesper Dangaard Brouer
2017-10-11T05:36:39Z

On Wed, 11 Oct 2017 00:48:40 +0200
Daniel Borkmann <daniel@iogearbox.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