Unfortunately, __builtin_dynamic_object_size() does not take into account flexible array sizes, even when they are sized by __counted_by. As a result, the size tests for the flexible arrays need to be separated to get an accurate check of the compiler's behavior. While at it, fully test sizeof, __struct_size (bdos(..., 0)), and __member_size (bdos(..., 1)).
I still think this is a compiler design issue, but there's not much to be done about it currently beyond adjusting these tests. GCC and Clang agree on this behavior at least. :) Reported-by: "Thomas Weißschuh" <li...@weissschuh.net> Closes: https://lore.kernel.org/lkml/e1a1531d-6968-4ae8-a3b5-5ea0547ec...@t-8ch.de/ Fixes: 9dd5134c6158 ("kunit/overflow: Adjust for __counted_by with DEFINE_RAW_FLEX()") Signed-off-by: Kees Cook <k...@kernel.org> --- Cc: Nathan Chancellor <nat...@kernel.org> Cc: "Gustavo A. R. Silva" <gustavo...@kernel.org> Cc: linux-hardening@vger.kernel.org --- lib/overflow_kunit.c | 38 ++++++++++++++++++++++++++++---------- 1 file changed, 28 insertions(+), 10 deletions(-) diff --git a/lib/overflow_kunit.c b/lib/overflow_kunit.c index 5222c6393f11..894691b4411a 100644 --- a/lib/overflow_kunit.c +++ b/lib/overflow_kunit.c @@ -1185,22 +1185,40 @@ struct bar { static void DEFINE_FLEX_test(struct kunit *test) { - /* Using _RAW_ on a __counted_by struct will initialize "counter" to zero */ - DEFINE_RAW_FLEX(struct foo, two_but_zero, array, 2); -#ifdef CONFIG_CC_HAS_COUNTED_BY - int expected_raw_size = sizeof(struct foo); -#else - int expected_raw_size = sizeof(struct foo) + 2 * sizeof(s16); -#endif - /* Without annotation, it will always be on-stack size. */ DEFINE_RAW_FLEX(struct bar, two, array, 2); DEFINE_FLEX(struct foo, eight, array, counter, 8); DEFINE_FLEX(struct foo, empty, array, counter, 0); + /* Using _RAW_ on a __counted_by struct will initialize "counter" to zero */ + DEFINE_RAW_FLEX(struct foo, two_but_zero, array, 2); + int array_size_override = 0; - KUNIT_EXPECT_EQ(test, __struct_size(two_but_zero), expected_raw_size); + KUNIT_EXPECT_EQ(test, sizeof(*two), sizeof(struct bar)); KUNIT_EXPECT_EQ(test, __struct_size(two), sizeof(struct bar) + 2 * sizeof(s16)); - KUNIT_EXPECT_EQ(test, __struct_size(eight), 24); + KUNIT_EXPECT_EQ(test, __member_size(two), sizeof(struct bar) + 2 * sizeof(s16)); + KUNIT_EXPECT_EQ(test, __struct_size(two->array), 2 * sizeof(s16)); + KUNIT_EXPECT_EQ(test, __member_size(two->array), 2 * sizeof(s16)); + + KUNIT_EXPECT_EQ(test, sizeof(*eight), sizeof(struct foo)); + KUNIT_EXPECT_EQ(test, __struct_size(eight), sizeof(struct foo) + 8 * sizeof(s16)); + KUNIT_EXPECT_EQ(test, __member_size(eight), sizeof(struct foo) + 8 * sizeof(s16)); + KUNIT_EXPECT_EQ(test, __struct_size(eight->array), 8 * sizeof(s16)); + KUNIT_EXPECT_EQ(test, __member_size(eight->array), 8 * sizeof(s16)); + + KUNIT_EXPECT_EQ(test, sizeof(*empty), sizeof(struct foo)); KUNIT_EXPECT_EQ(test, __struct_size(empty), sizeof(struct foo)); + KUNIT_EXPECT_EQ(test, __member_size(empty), sizeof(struct foo)); + KUNIT_EXPECT_EQ(test, __struct_size(empty->array), 0); + KUNIT_EXPECT_EQ(test, __member_size(empty->array), 0); + + /* If __counted_by is not being used, array size will have the on-stack size. */ + if (!IS_ENABLED(CONFIG_CC_HAS_COUNTED_BY)) + array_size_override = 2 * sizeof(s16); + + KUNIT_EXPECT_EQ(test, sizeof(*two_but_zero), sizeof(struct foo)); + KUNIT_EXPECT_EQ(test, __struct_size(two_but_zero), sizeof(struct foo) + 2 * sizeof(s16)); + KUNIT_EXPECT_EQ(test, __member_size(two_but_zero), sizeof(struct foo) + 2 * sizeof(s16)); + KUNIT_EXPECT_EQ(test, __struct_size(two_but_zero->array), array_size_override); + KUNIT_EXPECT_EQ(test, __member_size(two_but_zero->array), array_size_override); } static struct kunit_case overflow_test_cases[] = { -- 2.34.1
