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: 246331e3f1ea ("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

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 580d07b154715164d387dbc4866ad20689198567..feabc01938525886bd105bce4d878d71f05be8b2 100644 (file)
--- a/kernel/bpf/arraymap.c
+++ b/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 */