@@ -130,10 +130,12 @@ static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
cost = (u64) sizeof(struct list_head) * num_possible_cpus();
if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
- dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
-
- if (!dtab->n_buckets) /* Overflow check */
+ /* hash table size must be power of 2; roundup_pow_of_two() can
+ * overflow into UB on 32-bit arches, so check that first
+ */
+ if (dtab->map.max_entries > 1UL << 31)
return -EINVAL;
+ dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
cost += (u64) sizeof(struct hlist_head) * dtab->n_buckets;
} else {
cost += (u64) dtab->map.max_entries * sizeof(struct bpf_dtab_netdev *);