[PATCH] lib: stackinit: Convert to KUnit

Kees Cook
2022-02-24T05:51:58Z

Convert to running under Kunit (and retain being able to run stand-alone
too). Building under Clang (or GCC 12) with CONFIG_INIT_STACK_ALL_ZERO=y,
this now passes as expected:

$ ./tools/testing/kunit/kunit.py config --make_option LLVM=1
$ ./tools/testing/kunit/kunit.py run overflow --make_option LLVM=1 \
--kconfig_add CONFIG_INIT_STACK_ALL_ZERO=y
...
[09:47:28] ================= stackinit (65 subtests) ==================
[09:47:28] [PASSED] test_u8_zero
[09:47:28] [PASSED] test_u16_zero
[09:47:28] [PASSED] test_u32_zero
[09:47:28] [PASSED] test_u64_zero
[09:47:28] [PASSED] test_char_array_zero
[09:47:28] [PASSED] test_small_hole_zero
[09:47:28] [PASSED] test_big_hole_zero
[09:47:28] [PASSED] test_trailing_hole_zero
[09:47:28] [PASSED] test_packed_zero
[09:47:28] [PASSED] test_small_hole_dynamic_partial
[09:47:28] [PASSED] test_big_hole_dynamic_partial
[09:47:28] [PASSED] test_trailing_hole_dynamic_partial
[09:47:28] [PASSED] test_packed_dynamic_partial
[09:47:28] [PASSED] test_small_hole_assigned_dynamic_partial
[09:47:28] [PASSED] test_big_hole_assigned_dynamic_partial
[09:47:28] [PASSED] test_trailing_hole_assigned_dynamic_partial
[09:47:28] [PASSED] test_packed_assigned_dynamic_partial
[09:47:28] [PASSED] test_small_hole_static_partial
[09:47:28] [PASSED] test_big_hole_static_partial
[09:47:28] [PASSED] test_trailing_hole_static_partial
[09:47:28] [PASSED] test_packed_static_partial
[09:47:28] [PASSED] test_small_hole_static_all
[09:47:28] [PASSED] test_big_hole_static_all
[09:47:28] [PASSED] test_trailing_hole_static_all
[09:47:28] [PASSED] test_packed_static_all
[09:47:28] [PASSED] test_small_hole_dynamic_all
[09:47:28] [PASSED] test_big_hole_dynamic_all
[09:47:28] [PASSED] test_trailing_hole_dynamic_all
[09:47:28] [PASSED] test_packed_dynamic_all
[09:47:28] [PASSED] test_small_hole_runtime_partial
[09:47:28] [PASSED] test_big_hole_runtime_partial
[09:47:28] [PASSED] test_trailing_hole_runtime_partial
[09:47:28] [PASSED] test_packed_runtime_partial
[09:47:28] [PASSED] test_small_hole_runtime_all
[09:47:28] [PASSED] test_big_hole_runtime_all
[09:47:28] [PASSED] test_trailing_hole_runtime_all
[09:47:28] [PASSED] test_packed_runtime_all
[09:47:28] [PASSED] test_small_hole_assigned_static_partial
[09:47:28] [PASSED] test_big_hole_assigned_static_partial
[09:47:28] [PASSED] test_trailing_hole_assigned_static_partial
[09:47:28] [PASSED] test_packed_assigned_static_partial
[09:47:28] [PASSED] test_small_hole_assigned_static_all
[09:47:28] [PASSED] test_big_hole_assigned_static_all
[09:47:28] [PASSED] test_trailing_hole_assigned_static_all
[09:47:28] [PASSED] test_packed_assigned_static_all
[09:47:28] [PASSED] test_small_hole_assigned_dynamic_all
[09:47:28] [PASSED] test_big_hole_assigned_dynamic_all
[09:47:28] [PASSED] test_trailing_hole_assigned_dynamic_all
[09:47:28] [PASSED] test_packed_assigned_dynamic_all
[09:47:28] [SKIPPED] test_small_hole_assigned_copy
[09:47:28] [SKIPPED] test_big_hole_assigned_copy
[09:47:28] [SKIPPED] test_trailing_hole_assigned_copy
[09:47:28] [PASSED] test_packed_assigned_copy
[09:47:28] [PASSED] test_u8_none
[09:47:28] [PASSED] test_u16_none
[09:47:28] [PASSED] test_u32_none
[09:47:28] [PASSED] test_u64_none
[09:47:28] [PASSED] test_char_array_none
[09:47:28] [SKIPPED] test_switch_1_none
[09:47:28] [SKIPPED] test_switch_2_none
[09:47:28] [PASSED] test_small_hole_none
[09:47:28] [PASSED] test_big_hole_none
[09:47:28] [PASSED] test_trailing_hole_none
[09:47:28] [PASSED] test_packed_none
[09:47:28] [PASSED] test_user
[09:47:28] ==================== [PASSED] stackinit ====================
[09:47:28] ============================================================
[09:47:28] Testing complete. Passed: 60, Failed: 0, Crashed: 0, Skipped: 5, Errors: 0
[09:47:28] Elapsed time: 4.192s total, 0.001s configuring, 4.070s building, 0.102s running

Cc: David Gow <davidgow@google.com>
Cc: Daniel Latypov <dlatypov@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
lib/Kconfig.debug | 26 +-
lib/Makefile | 4 +-
lib/{test_stackinit.c => stackinit_kunit.c} | 249 ++++++++++++--------
3 files changed, 168 insertions(+), 111 deletions(-)
rename lib/{test_stackinit.c => stackinit_kunit.c} (73%)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 14d90d03bc8d..ea4415275563 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2511,6 +2511,21 @@ config OVERFLOW_KUNIT_TEST

If unsure, say N.

+config STACKINIT_KUNIT_TEST
+ tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
+ depends on KUNIT
+ default KUNIT_ALL_TESTS
+ help
+ Test if the kernel is zero-initializing stack variables and
+ padding. Coverage is controlled by compiler flags,
+ CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
+ or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
+
+ For more information on KUnit and unit tests in general please refer
+ to the KUnit documentation in Documentation/dev-tools/kunit/.
+
+ If unsure, say N.
+
config TEST_UDELAY
tristate "udelay test driver"
help
@@ -2602,17 +2617,6 @@ config TEST_OBJAGG
Enable this option to test object aggregation manager on boot
(or module load).

-
-config TEST_STACKINIT
- tristate "Test level of stack variable initialization"
- help
- Test if the kernel is zero-initializing stack variables and
- padding. Coverage is controlled by compiler flags,
- CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
- or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
-
- If unsure, say N.
-
config TEST_MEMINIT
tristate "Test heap/page initialization"
help
diff --git a/lib/Makefile b/lib/Makefile
index fdfcbfaff32f..353bc09ce38d 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -93,8 +93,6 @@ obj-$(CONFIG_TEST_KMOD) += test_kmod.o
obj-$(CONFIG_TEST_DEBUG_VIRTUAL) += test_debug_virtual.o
obj-$(CONFIG_TEST_MEMCAT_P) += test_memcat_p.o
obj-$(CONFIG_TEST_OBJAGG) += test_objagg.o
-CFLAGS_test_stackinit.o += $(call cc-disable-warning, switch-unreachable)
-obj-$(CONFIG_TEST_STACKINIT) += test_stackinit.o
obj-$(CONFIG_TEST_BLACKHOLE_DEV) += test_blackhole_dev.o
obj-$(CONFIG_TEST_MEMINIT) += test_meminit.o
obj-$(CONFIG_TEST_LOCKUP) += test_lockup.o
@@ -363,6 +361,8 @@ obj-$(CONFIG_CMDLINE_KUNIT_TEST) += cmdline_kunit.o
obj-$(CONFIG_SLUB_KUNIT_TEST) += slub_kunit.o
obj-$(CONFIG_MEMCPY_KUNIT_TEST) += memcpy_kunit.o
obj-$(CONFIG_OVERFLOW_KUNIT_TEST) += overflow_kunit.o
+CFLAGS_stackinit_kunit.o += $(call cc-disable-warning, switch-unreachable)
+obj-$(CONFIG_STACKINIT_KUNIT_TEST) += stackinit_kunit.o

obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o

diff --git a/lib/test_stackinit.c b/lib/stackinit_kunit.c
similarity index 73%
rename from lib/test_stackinit.c
rename to lib/stackinit_kunit.c
index a3c74e6a21ff..72c7d4cb8ed2 100644
--- a/lib/test_stackinit.c
+++ b/lib/stackinit_kunit.c
@@ -2,14 +2,23 @@
/*
* Test cases for compiler-based stack variable zeroing via
* -ftrivial-auto-var-init={zero,pattern} or CONFIG_GCC_PLUGIN_STRUCTLEAK*.
+ * For example, see:
+ * https://www.kernel.org/doc/html/latest/dev-tools/kunit/kunit-tool.html#configuring-building-and-running-tests
+ * ./tools/testing/kunit/kunit.py config --make_option LLVM=1
+ * ./tools/testing/kunit/kunit.py run overflow [--raw_output] \
+ * --make_option LLVM=1 \
+ * --kconfig_add CONFIG_INIT_STACK_ALL_ZERO=y
*
* External build example:
* clang -O2 -Wall -ftrivial-auto-var-init=pattern \
- * -o test_stackinit test_stackinit.c
+ * -o stackinit_kunit stackinit_kunit.c
+ * ./stackinit_kunit
+ *
*/
#ifdef __KERNEL__
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

+#include <kunit/test.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
@@ -18,21 +27,55 @@
#else

/* Userspace headers. */
+#define _GNU_SOURCE
#include <stdio.h>
#include <stdint.h>
+#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <errno.h>
#include <sys/types.h>

/* Linux kernel-ism stubs for stand-alone userspace build. */
-#define KBUILD_MODNAME "stackinit"
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-#define pr_err(fmt, ...) fprintf(stderr, pr_fmt(fmt), ##__VA_ARGS__)
-#define pr_warn(fmt, ...) fprintf(stderr, pr_fmt(fmt), ##__VA_ARGS__)
-#define pr_info(fmt, ...) fprintf(stdout, pr_fmt(fmt), ##__VA_ARGS__)
-#define __init /**/
-#define __exit /**/
+#define TEST_PASS 0
+#define TEST_SKIP 1
+#define TEST_FAIL 2
+struct kunit {
+ int status;
+ char *msg;
+};
+struct kunit_case {
+ void (*run_case)(struct kunit *test);
+ const char *name;
+};
+struct kunit_suite {
+ const char *name;
+ const struct kunit_case *test_cases;
+};
+#define KUNIT_CASE(test_name) { .run_case = test_name, .name = #test_name }
+
+#define KUNIT_ASSERT_TRUE_MSG(test, expr, fmt, ...) \
+do { \
+ if (!(expr)) { \
+ if (test->status != TEST_SKIP) \
+ test->status = TEST_FAIL; \
+ if (test->msg) \
+ free(test->msg); \
+ asprintf(&test->msg, fmt, ##__VA_ARGS__); \
+ } \
+} while (0)
+
+#define KUNIT_ASSERT_EQ_MSG(test, left, right, fmt, ...) \
+ KUNIT_ASSERT_TRUE_MSG(test, (left) == (right), fmt, ##__VA_ARGS__)
+
+#define kunit_skip(test, fmt, ...) \
+do { \
+ test->status = TEST_SKIP; \
+ if (test->msg) \
+ free(test->msg); \
+ asprintf(&test->msg, fmt, ##__VA_ARGS__); \
+} while (0)
+
#define __user /**/
#define noinline __attribute__((__noinline__))
#define __aligned(x) __attribute__((__aligned__(x)))
@@ -59,16 +102,44 @@ typedef uint16_t u16;
typedef uint32_t u32;
typedef uint64_t u64;

-#define module_init(func) static int (*do_init)(void) = func
-#define module_exit(func) static void (*do_exit)(void) = func
-#define MODULE_LICENSE(str) int main(void) { \
- int rc; \
- /* License: str */ \
- rc = do_init(); \
- if (rc == 0) \
- do_exit(); \
- return rc; \
- }
+#define MODULE_LICENSE(str) /* */
+
+int do_kunit_test_suite(struct kunit_suite *suite)
+{
+ const struct kunit_case *test_case;
+ int rc = 0;
+
+ for (test_case = suite->test_cases; test_case->run_case; test_case++) {
+ struct kunit test = { };
+
+ test_case->run_case(&test);
+ switch (test.status) {
+ default:
+ case TEST_FAIL:
+ fprintf(stderr, "FAIL: %s%s%s", test_case->name,
+ test.msg ? ": " : "",
+ test.msg ?: "\n");
+ rc = 1;
+ break;
+ case TEST_SKIP:
+ fprintf(stdout, "XFAIL: %s%s%s", test_case->name,
+ test.msg ? ": " : "",
+ test.msg ?: "\n");
+ break;
+ case TEST_PASS:
+ fprintf(stdout, "ok: %s\n", test_case->name);
+ break;
+ }
+ if (test.msg)
+ free(test.msg);
+ }
+ return rc;
+}
+
+#define kunit_test_suite(suite) \
+int main(void) { \
+ return do_kunit_test_suite(&(suite)); \
+}

#endif /* __KERNEL__ */

@@ -201,7 +272,7 @@ static bool range_contains(char *haystack_start, size_t haystack_size,
*/
#define DEFINE_TEST_DRIVER(name, var_type, which, xfail) \
/* Returns 0 on success, 1 on failure. */ \
-static noinline __init int test_ ## name (void) \
+static noinline void test_ ## name (struct kunit *test) \
{ \
var_type zero INIT_CLONE_ ## which; \
int ignored; \
@@ -220,10 +291,8 @@ static noinline __init int test_ ## name (void) \
/* Verify all bytes overwritten with 0xFF. */ \
for (sum = 0, i = 0; i < target_size; i++) \
sum += (check_buf[i] != 0xFF); \
- if (sum) { \
- pr_err(#name ": leaf fill was not 0xFF!?\n"); \
- return 1; \
- } \
+ KUNIT_ASSERT_EQ_MSG(test, sum, 0, \
+ "leaf fill was not 0xFF!?\n"); \
/* Clear entire check buffer for later bit tests. */ \
memset(check_buf, 0x00, sizeof(check_buf)); \
/* Extract stack-defined variable contents. */ \
@@ -231,32 +300,29 @@ static noinline __init int test_ ## name (void) \
FETCH_ARG_ ## which(zero)); \
\
/* Validate that compiler lined up fill and target. */ \
- if (!range_contains(fill_start, fill_size, \
- target_start, target_size)) { \
- pr_err(#name ": stack fill missed target!?\n"); \
- pr_err(#name ": fill %zu wide\n", fill_size); \
- pr_err(#name ": target offset by %d\n", \
- (int)((ssize_t)(uintptr_t)fill_start - \
- (ssize_t)(uintptr_t)target_start)); \
- return 1; \
- } \
+ KUNIT_ASSERT_TRUE_MSG(test, \
+ range_contains(fill_start, fill_size, \
+ target_start, target_size), \
+ "stack fill missed target!? " \
+ "(fill %zu wide, target offset by %d)\n", \
+ fill_size, \
+ (int)((ssize_t)(uintptr_t)fill_start - \
+ (ssize_t)(uintptr_t)target_start)); \
\
/* Look for any bytes still 0xFF in check region. */ \
for (sum = 0, i = 0; i < target_size; i++) \
sum += (check_buf[i] == 0xFF); \
\
- if (sum == 0) { \
- pr_info(#name " ok\n"); \
- return 0; \
- } else { \
- pr_warn(#name " %sFAIL (uninit bytes: %d)\n", \
- (xfail) ? "X" : "", sum); \
- return (xfail) ? 0 : 1; \
- } \
+ if (sum != 0 && xfail) \
+ kunit_skip(test, \
+ "XFAIL uninit bytes: %d\n", \
+ sum); \
+ KUNIT_ASSERT_EQ_MSG(test, sum, 0, \
+ "uninit bytes: %d\n", sum); \
}
#define DEFINE_TEST(name, var_type, which, init_level, xfail) \
/* no-op to force compiler into ignoring "uninitialized" vars */\
-static noinline __init DO_NOTHING_TYPE_ ## which(var_type) \
+static noinline DO_NOTHING_TYPE_ ## which(var_type) \
do_nothing_ ## name(var_type *ptr) \
{ \
/* Will always be true, but compiler doesn't know. */ \
@@ -265,9 +331,8 @@ do_nothing_ ## name(var_type *ptr) \
else \
return DO_NOTHING_RETURN_ ## which(ptr + 1); \
} \
-static noinline __init int leaf_ ## name(unsigned long sp, \
- bool fill, \
- var_type *arg) \
+static noinline int leaf_ ## name(unsigned long sp, bool fill, \
+ var_type *arg) \
{ \
char buf[VAR_BUFFER]; \
var_type var \
@@ -398,7 +463,7 @@ static int noinline __leaf_switch_none(int path, bool fill)
* This is intentionally unreachable. To silence the
* warning, build with -Wno-switch-unreachable
*/
- uint64_t var;
+ uint64_t var[10];

case 1:
target_start = &var;
@@ -423,19 +488,19 @@ static int noinline __leaf_switch_none(int path, bool fill)
memcpy(check_buf, target_start, target_size);
break;
default:
- var = 5;
- return var & forced_mask;
+ var[1] = 5;
+ return var[1] & forced_mask;
}
return 0;
}

-static noinline __init int leaf_switch_1_none(unsigned long sp, bool fill,
+static noinline int leaf_switch_1_none(unsigned long sp, bool fill,
uint64_t *arg)
{
return __leaf_switch_none(1, fill);
}

-static noinline __init int leaf_switch_2_none(unsigned long sp, bool fill,
+static noinline int leaf_switch_2_none(unsigned long sp, bool fill,
uint64_t *arg)
{
return __leaf_switch_none(2, fill);
@@ -450,65 +515,53 @@ static noinline __init int leaf_switch_2_none(unsigned long sp, bool fill,
DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR, XFAIL);
DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR, XFAIL);

-static int __init test_stackinit_init(void)
-{
- unsigned int failures = 0;
-
-#define test_scalars(init) do { \
- failures += test_u8_ ## init (); \
- failures += test_u16_ ## init (); \
- failures += test_u32_ ## init (); \
- failures += test_u64_ ## init (); \
- failures += test_char_array_ ## init (); \
- } while (0)
+#define KUNIT_test_scalars(init) \
+ KUNIT_CASE(test_u8_ ## init), \
+ KUNIT_CASE(test_u16_ ## init), \
+ KUNIT_CASE(test_u32_ ## init), \
+ KUNIT_CASE(test_u64_ ## init), \
+ KUNIT_CASE(test_char_array_ ## init)

-#define test_structs(init) do { \
- failures += test_small_hole_ ## init (); \
- failures += test_big_hole_ ## init (); \
- failures += test_trailing_hole_ ## init (); \
- failures += test_packed_ ## init (); \
- } while (0)
+#define KUNIT_test_structs(init) \
+ KUNIT_CASE(test_small_hole_ ## init), \
+ KUNIT_CASE(test_big_hole_ ## init), \
+ KUNIT_CASE(test_trailing_hole_ ## init),\
+ KUNIT_CASE(test_packed_ ## init) \

+static struct kunit_case stackinit_test_cases[] = {
/* These are explicitly initialized and should always pass. */
- test_scalars(zero);
- test_structs(zero);
+ KUNIT_test_scalars(zero),
+ KUNIT_test_structs(zero),
/* Padding here appears to be accidentally always initialized? */
- test_structs(dynamic_partial);
- test_structs(assigned_dynamic_partial);
+ KUNIT_test_structs(dynamic_partial),
+ KUNIT_test_structs(assigned_dynamic_partial),
/* Padding initialization depends on compiler behaviors. */
- test_structs(static_partial);
- test_structs(static_all);
- test_structs(dynamic_all);
- test_structs(runtime_partial);
- test_structs(runtime_all);
- test_structs(assigned_static_partial);
- test_structs(assigned_static_all);
- test_structs(assigned_dynamic_all);
+ KUNIT_test_structs(static_partial),
+ KUNIT_test_structs(static_all),
+ KUNIT_test_structs(dynamic_all),
+ KUNIT_test_structs(runtime_partial),
+ KUNIT_test_structs(runtime_all),
+ KUNIT_test_structs(assigned_static_partial),
+ KUNIT_test_structs(assigned_static_all),
+ KUNIT_test_structs(assigned_dynamic_all),
/* Everything fails this since it effectively performs a memcpy(). */
- test_structs(assigned_copy);
-
+ KUNIT_test_structs(assigned_copy),
/* STRUCTLEAK_BYREF_ALL should cover everything from here down. */
- test_scalars(none);
- failures += test_switch_1_none();
- failures += test_switch_2_none();
-
+ KUNIT_test_scalars(none),
+ KUNIT_CASE(test_switch_1_none),
+ KUNIT_CASE(test_switch_2_none),
/* STRUCTLEAK_BYREF should cover from here down. */
- test_structs(none);
-
+ KUNIT_test_structs(none),
/* STRUCTLEAK will only cover this. */
- failures += test_user();
-
- if (failures == 0)
- pr_info("all tests passed!\n");
- else
- pr_err("failures: %u\n", failures);
+ KUNIT_CASE(test_user),
+ {}
+};

- return failures ? -EINVAL : 0;
-}
-module_init(test_stackinit_init);
+static struct kunit_suite stackinit_test_suite = {
+ .name = "stackinit",
+ .test_cases = stackinit_test_cases,
+};

-static void __exit test_stackinit_exit(void)
-{ }
-module_exit(test_stackinit_exit);
+kunit_test_suite(stackinit_test_suite);

MODULE_LICENSE("GPL");
--
2.30.2