bpf: fix possible endless loop in BPF map iteration

The _safe variant used here gets the next element before running the callback,
avoiding the endless loop condition.

Signed-off-by: Brandon Kammerdiener <brandon.kammerdiener@intel.com>
Link: https://lore.kernel.org/r/20250424153246.141677-2-brandon.kammerdiener@intel.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Hou Tao <houtao1@huawei.com>

diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 5a5adc6..92b606d 100644 (file)
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -2189,7 +2189,7 @@ static long bpf_for_each_hash_elem(struct bpf_map *map, bpf_callback_t callback_
                b = &htab->buckets[i];
                rcu_read_lock();
                head = &b->head;
-               hlist_nulls_for_each_entry_rcu(elem, n, head, hash_node) {
+               hlist_nulls_for_each_entry_safe(elem, n, head, hash_node) {
                        key = elem->key;
                        if (is_percpu) {
                                /* current cpu value for percpu map */