From: Kees Cook Date: Wed, 12 Mar 2025 00:03:56 +0000 (-0700) Subject: kunit/fortify: Expand testing of __compiletime_strlen() X-Git-Tag: v6.15-rc1~234^2~8 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=416cf1f4d91bf52305cd160a382273ccef980b7f;p=thirdparty%2Flinux.git kunit/fortify: Expand testing of __compiletime_strlen() It seems that Clang thinks __builtin_constant_p() of undefined variables should return true[1]. This is being fixed separately[2], but in the meantime, expand the fortify tests to help track this kind of thing down faster in the future. Link: https://github.com/ClangBuiltLinux/linux/issues/2073 [1] Link: https://github.com/llvm/llvm-project/pull/130713 [2] Link: https://lore.kernel.org/r/20250312000349.work.786-kees@kernel.org Signed-off-by: Kees Cook --- diff --git a/lib/tests/fortify_kunit.c b/lib/tests/fortify_kunit.c index ecb638d4cde1e..18dcdedf777fa 100644 --- a/lib/tests/fortify_kunit.c +++ b/lib/tests/fortify_kunit.c @@ -60,6 +60,7 @@ static int fortify_write_overflows; static const char array_of_10[] = "this is 10"; static const char *ptr_of_11 = "this is 11!"; +static const char * const unchanging_12 = "this is 12!!"; static char array_unknown[] = "compiler thinks I might change"; void fortify_add_kunit_error(int write) @@ -83,12 +84,28 @@ void fortify_add_kunit_error(int write) static void fortify_test_known_sizes(struct kunit *test) { + char stack[80] = "Test!"; + + KUNIT_EXPECT_FALSE(test, __is_constexpr(__builtin_strlen(stack))); + KUNIT_EXPECT_EQ(test, __compiletime_strlen(stack), 5); + + KUNIT_EXPECT_TRUE(test, __is_constexpr(__builtin_strlen("88888888"))); KUNIT_EXPECT_EQ(test, __compiletime_strlen("88888888"), 8); + + KUNIT_EXPECT_TRUE(test, __is_constexpr(__builtin_strlen(array_of_10))); KUNIT_EXPECT_EQ(test, __compiletime_strlen(array_of_10), 10); + + KUNIT_EXPECT_FALSE(test, __is_constexpr(__builtin_strlen(ptr_of_11))); KUNIT_EXPECT_EQ(test, __compiletime_strlen(ptr_of_11), 11); + KUNIT_EXPECT_TRUE(test, __is_constexpr(__builtin_strlen(unchanging_12))); + KUNIT_EXPECT_EQ(test, __compiletime_strlen(unchanging_12), 12); + + KUNIT_EXPECT_FALSE(test, __is_constexpr(__builtin_strlen(array_unknown))); KUNIT_EXPECT_EQ(test, __compiletime_strlen(array_unknown), SIZE_MAX); + /* Externally defined and dynamically sized string pointer: */ + KUNIT_EXPECT_FALSE(test, __is_constexpr(__builtin_strlen(test->name))); KUNIT_EXPECT_EQ(test, __compiletime_strlen(test->name), SIZE_MAX); }