[PATCH bpf-next 1/2] bpf: btf: Check array t->size

[Martin KaFai Lau]

This patch ensures array's t->size is 0.

The array size is decided by its individual elem's size and the
number of elements.  Hence, t->size is not used and
it must be 0.

A test case is added to test_btf.c

Signed-off-by: Martin KaFai Lau <ka...@fb.com>
---
 kernel/bpf/btf.c                       |  5 +++++
 tools/testing/selftests/bpf/test_btf.c | 23 +++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 3d20aa1f4b54..84ad532f2854 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -1342,6 +1342,11 @@ static s32 btf_array_check_meta(struct btf_verifier_env 
*env,
                return -EINVAL;
        }
 
+       if (t->size) {
+               btf_verifier_log_type(env, t, "size != 0");
+               return -EINVAL;
+       }
+
        /* Array elem type and index type cannot be in type void,
         * so !array->type and !array->index_type are not allowed.
         */
diff --git a/tools/testing/selftests/bpf/test_btf.c 
b/tools/testing/selftests/bpf/test_btf.c
index 35064df688c1..fd8246e84149 100644
--- a/tools/testing/selftests/bpf/test_btf.c
+++ b/tools/testing/selftests/bpf/test_btf.c
@@ -1179,6 +1179,29 @@ static struct btf_raw_test raw_tests[] = {
 },
 
 {
+       .descr = "array test. t->size != 0\"",
+       .raw_types = {
+               /* int */                               /* [1] */
+               BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
+               /* int[16] */                           /* [2] */
+               BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_ARRAY, 0, 0), 1),
+               BTF_ARRAY_ENC(1, 1, 16),
+               BTF_END_RAW,
+       },
+       .str_sec = "",
+       .str_sec_size = sizeof(""),
+       .map_type = BPF_MAP_TYPE_ARRAY,
+       .map_name = "array_test_map",
+       .key_size = sizeof(int),
+       .value_size = sizeof(int),
+       .key_type_id = 1,
+       .value_type_id = 1,
+       .max_entries = 4,
+       .btf_load_err = true,
+       .err_str = "size != 0",
+},
+
+{
        .descr = "int test. invalid int_data",
        .raw_types = {
                BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), 4),
-- 
2.9.5