Commit cba41bb7 authored by Rhys Rustad-Elliott's avatar Rhys Rustad-Elliott Committed by Martin KaFai Lau
Browse files

bpf: Fix elem_size not being set for inner maps 



Commit d937bc34 ("bpf: make uniform use of array->elem_size
everywhere in arraymap.c") changed array_map_gen_lookup to use
array->elem_size instead of round_up(map->value_size, 8) as the element
size when generating code to access a value in an array map.

array->elem_size, however, is not set by bpf_map_meta_alloc when
initializing an BPF_MAP_TYPE_ARRAY_OF_MAPS or BPF_MAP_TYPE_HASH_OF_MAPS.
This results in array_map_gen_lookup incorrectly outputting code that
always accesses index 0 in the array (as the index will be calculated
via a multiplication with the element size, which is incorrectly set to
0).

Set elem_size on the bpf_array object when allocating an array or hash
of maps to fix this.

Fixes: d937bc34 ("bpf: make uniform use of array->elem_size everywhere in arraymap.c")
Signed-off-by: default avatarRhys Rustad-Elliott <me@rhysre.net>
Link: https://lore.kernel.org/r/20230602190110.47068-2-me@rhysre.net


Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
parent b0fd1852

kernel/bpf/map_in_map.c

+6 −2
Original line number Diff line number Diff line
@@ -69,9 +69,13 @@ struct bpf_map *bpf_map_meta_alloc(int inner_map_ufd) 
	/* Misc members not needed in bpf_map_meta_equal() check. */

	inner_map_meta->ops = inner_map->ops;

	if (inner_map->ops == &array_map_ops) {

		struct bpf_array *inner_array_meta =

			container_of(inner_map_meta, struct bpf_array, map);

		struct bpf_array *inner_array = container_of(inner_map, struct bpf_array, map);



		inner_array_meta->index_mask = inner_array->index_mask;

		inner_array_meta->elem_size = inner_array->elem_size;

		inner_map_meta->bypass_spec_v1 = inner_map->bypass_spec_v1;

		container_of(inner_map_meta, struct bpf_array, map)->index_mask =

		     container_of(inner_map, struct bpf_array, map)->index_mask;

	}



	fdput(f);