selftests/bpf: Add BTF repeated field count overflow test

Add a raw BTF test that exercises repeated special-field expansion with a
large array count. The compact element layout keeps the array byte size
representable while the repeated field count overflows the old u32 capacity
calculation in btf_repeat_fields().

Signed-off-by: Paul Moses <p@1g4.org>
Link: https://lore.kernel.org/bpf/SzebdWqm2zREZBf8Tc5Kc-JDWbh9nBztnk4PUu5kRSD1OOdr_ESVTt__2Hd3-lClr47jIjJCXfOH0RHsMpjjpEUh_R2v30nh3T1IXNT6Pbo=@1g4.org
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

diff --git a/tools/testing/selftests/bpf/prog_tests/btf.c b/tools/testing/selftests/bpf/prog_tests/btf.c
index a9de328a869768ca1e0721b242785b9a057ba1f4..96f719a0cec9d41f876dc6125cdfaad3d3a62ca5 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/btf.c
+++ b/tools/testing/selftests/bpf/prog_tests/btf.c
@@ -4258,6 +4258,43 @@ static struct btf_raw_test raw_tests[] = {
        .max_entries = 1,
 },
 
+{
+       .descr = "struct test repeated fields count overflow",
+       .raw_types = {
+               BTF_TYPE_INT_ENC(NAME_TBD, BTF_INT_SIGNED, 0, 32, 4),   /* [1] */
+               BTF_STRUCT_ENC(NAME_TBD, 0, 0),                         /* [2] */
+               BTF_TYPE_TAG_ENC(NAME_TBD, 2),                          /* [3] */
+               BTF_PTR_ENC(3),                                         /* [4] */
+               BTF_TYPE_ARRAY_ENC(4, 1, 1),                            /* [5] */
+               BTF_STRUCT_ENC(NAME_TBD, 10, 8),                        /* [6] */
+               BTF_MEMBER_ENC(NAME_TBD, 5, 0),
+               BTF_MEMBER_ENC(NAME_TBD, 5, 0),
+               BTF_MEMBER_ENC(NAME_TBD, 5, 0),
+               BTF_MEMBER_ENC(NAME_TBD, 5, 0),
+               BTF_MEMBER_ENC(NAME_TBD, 5, 0),
+               BTF_MEMBER_ENC(NAME_TBD, 5, 0),
+               BTF_MEMBER_ENC(NAME_TBD, 5, 0),
+               BTF_MEMBER_ENC(NAME_TBD, 5, 0),
+               BTF_MEMBER_ENC(NAME_TBD, 5, 0),
+               BTF_MEMBER_ENC(NAME_TBD, 5, 0),
+               BTF_TYPE_ARRAY_ENC(6, 1, 0x1999999aU),                  /* [7] */
+               BTF_STRUCT_ENC(NAME_TBD, 2, 8 + 8 * 0x1999999aU),       /* [8] */
+               BTF_MEMBER_ENC(NAME_TBD, 4, 0),
+               BTF_MEMBER_ENC(NAME_TBD, 7, 64),
+               BTF_END_RAW,
+       },
+       BTF_STR_SEC("\0int\0prog_test_ref_kfunc\0kptr_untrusted\0elem"
+                   "\0p0\0p1\0p2\0p3\0p4\0p5\0p6\0p7\0p8\0p9"
+                   "\0outer\0trigger\0elems"),
+       .map_type = BPF_MAP_TYPE_ARRAY,
+       .map_name = "repeat_fields",
+       .key_size = sizeof(int),
+       .value_size = 8 + 8 * 0x1999999aU,
+       .key_type_id = 1,
+       .value_type_id = 8,
+       .max_entries = 1,
+       .btf_load_err = true,
+},
 }; /* struct btf_raw_test raw_tests[] */
 
 static const char *get_next_str(const char *start, const char *end)