[PATCH bpf] devmap: use bpf_map_area_alloc() for allocating hash buckets

[Toke Høiland-Jørgensen]

Syzkaller discovered that creating a hash of type devmap_hash with a large
number of entries can hit the memory allocator limit for allocating
contiguous memory regions. There's really no reason to use kmalloc_array()
directly in the devmap code, so just switch it to the existing
bpf_map_area_alloc() function that is used elsewhere.

Reported-by: Xiumei Mu <x...@redhat.com>
Fixes: 6f9d451ab1a3 ("xdp: Add devmap_hash map type for looking up devices by 
hashed index")
Signed-off-by: Toke Høiland-Jørgensen <t...@redhat.com>
---
 kernel/bpf/devmap.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 0cbb72cdaf63..5fdbc776a760 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -86,12 +86,13 @@ static DEFINE_PER_CPU(struct list_head, dev_flush_list);
 static DEFINE_SPINLOCK(dev_map_lock);
 static LIST_HEAD(dev_map_list);
 
-static struct hlist_head *dev_map_create_hash(unsigned int entries)
+static struct hlist_head *dev_map_create_hash(unsigned int entries,
+                                             int numa_node)
 {
        int i;
        struct hlist_head *hash;
 
-       hash = kmalloc_array(entries, sizeof(*hash), GFP_KERNEL);
+       hash = bpf_map_area_alloc(entries * sizeof(*hash), numa_node);
        if (hash != NULL)
                for (i = 0; i < entries; i++)
                        INIT_HLIST_HEAD(&hash[i]);
@@ -145,7 +146,8 @@ static int dev_map_init_map(struct bpf_dtab *dtab, union 
bpf_attr *attr)
                return -EINVAL;
 
        if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
-               dtab->dev_index_head = dev_map_create_hash(dtab->n_buckets);
+               dtab->dev_index_head = dev_map_create_hash(dtab->n_buckets,
+                                                          dtab->map.numa_node);
                if (!dtab->dev_index_head)
                        goto free_charge;
 
@@ -232,7 +234,7 @@ static void dev_map_free(struct bpf_map *map)
                        }
                }
 
-               kfree(dtab->dev_index_head);
+               bpf_map_area_free(dtab->dev_index_head);
        } else {
                for (i = 0; i < dtab->map.max_entries; i++) {
                        struct bpf_dtab_netdev *dev;
-- 
2.27.0