Re: [syzbot] Re: [syzbot] [bpf?] [net?] BUG: unable to handle kernel NULL pointer dereference in dev_map_hash_update_elem

syzbot
2024-02-27T13:52:24Z

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Subject: Re: [syzbot] [bpf?] [net?] BUG: unable to handle kernel NULL pointer dereference in dev_map_hash_update_elem
Author: toke@kernel.org

#syz test

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index a936c704d4e7..9b2286f9c6da 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -130,13 +130,11 @@ static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
bpf_map_init_from_attr(&dtab->map, attr);

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 */
+ if (dtab->map.max_entries > U32_MAX / 2)
return -EINVAL;
- }

- if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
+ dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
+
dtab->dev_index_head = dev_map_create_hash(dtab->n_buckets,
dtab->map.numa_node);
if (!dtab->dev_index_head)