diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index f9464e566f10..548eb1cc7c45 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -128,6 +128,7 @@ struct htab_elem { struct htab_btf_record { struct btf_record *record; + struct btf *btf; u32 key_size; }; @@ -497,8 +498,13 @@ static void htab_dtor_ctx_free(void *ctx) { struct htab_btf_record *hrec = ctx; + /* + * The duplicated record still points into the map BTF, so free it + * before dropping the reference that keeps that BTF alive. + */ btf_record_free(hrec->record); - kfree(ctx); + btf_put(hrec->btf); + kfree(hrec); } static int bpf_ma_set_dtor(struct bpf_map *map, struct bpf_mem_alloc *ma, @@ -521,6 +527,15 @@ static int bpf_ma_set_dtor(struct bpf_map *map, struct bpf_mem_alloc *ma, kfree(hrec); return err; } + /* + * btf_record_dup() only acquires kernel and module BTF. Fields whose + * types live in the map BTF keep pointing into it: kptrs to local + * types refer to map->btf, and graph roots carry a value record owned + * by its struct meta table. The context can outlive the map when the + * allocator defers its teardown, so hold a reference of our own. + */ + hrec->btf = map->btf; + btf_get(hrec->btf); bpf_mem_alloc_set_dtor(ma, dtor, htab_dtor_ctx_free, hrec); return 0; }