bpf: Do not walk twice the map on free

If someone stores both a timer and a workqueue in a map, on free
we would walk it twice.

Add a check in array_map_free_timers_wq and free the timers and
workqueues if they are present.

Fixes: 246331e3 ("bpf: allow struct bpf_wq to be embedded in arraymaps and hashmaps")
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20240430-bpf-next-v3-1-27afe7f3b17c@kernel.org

kernel/bpf/arraymap.c

@@ -436,13 +436,14 @@ static void array_map_free_timers_wq(struct bpf_map *map)
 	/* We don't reset or free fields other than timer and workqueue
 	 * on uref dropping to zero.
 	 */
-	if (btf_record_has_field(map->record, BPF_TIMER))
-		for (i = 0; i < array->map.max_entries; i++)
-			bpf_obj_free_timer(map->record, array_map_elem_ptr(array, i));
-
-	if (btf_record_has_field(map->record, BPF_WORKQUEUE))
-		for (i = 0; i < array->map.max_entries; i++)
-			bpf_obj_free_workqueue(map->record, array_map_elem_ptr(array, i));
+	if (btf_record_has_field(map->record, BPF_TIMER | BPF_WORKQUEUE)) {
+		for (i = 0; i < array->map.max_entries; i++) {
+			if (btf_record_has_field(map->record, BPF_TIMER))
+				bpf_obj_free_timer(map->record, array_map_elem_ptr(array, i));
+			if (btf_record_has_field(map->record, BPF_WORKQUEUE))
+				bpf_obj_free_workqueue(map->record, array_map_elem_ptr(array, i));
+		}
+	}
 }
 
 /* Called when map->refcnt goes to zero, either from workqueue or from syscall */