[PATCH v10 2/5] KUnit: KASAN Integration

David Gow
2020-08-01T07:10:11Z

From: Patricia Alfonso <trishalfonso@google.com>

Integrate KASAN into KUnit testing framework.
- Fail tests when KASAN reports an error that is not expected
- Use KUNIT_EXPECT_KASAN_FAIL to expect a KASAN error in KASAN
tests
- Expected KASAN reports pass tests and are still printed when run
without kunit_tool (kunit_tool still bypasses the report due to the
test passing)
- KUnit struct in current task used to keep track of the current
test from KASAN code

Make use of "[PATCH v3 kunit-next 1/2] kunit: generalize
kunit_resource API beyond allocated resources" and "[PATCH v3
kunit-next 2/2] kunit: add support for named resources" from Alan
Maguire [1]
- A named resource is added to a test when a KASAN report is
expected
- This resource contains a struct for kasan_data containing
booleans representing if a KASAN report is expected and if a
KASAN report is found

[1] (https://lore.kernel.org/linux-kselftest/1583251361-12748-1-git-send-email-alan.maguire@oracle.com/T/#t)

Signed-off-by: Patricia Alfonso <trishalfonso@google.com>
Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Brendan Higgins <brendanhiggins@google.com>
---
include/kunit/test.h | 5 +++++
include/linux/kasan.h | 6 ++++++
lib/kunit/test.c | 13 +++++++-----
lib/test_kasan.c | 47 +++++++++++++++++++++++++++++++++++++++++--
mm/kasan/report.c | 32 +++++++++++++++++++++++++++++
5 files changed, 96 insertions(+), 7 deletions(-)

diff --git a/include/kunit/test.h b/include/kunit/test.h
index 59f3144f009a..3391f38389f8 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -224,6 +224,11 @@ struct kunit {
struct list_head resources; /* Protected by lock. */
};

+static inline void kunit_set_failure(struct kunit *test)
+{
+ WRITE_ONCE(test->success, false);
+}
+
void kunit_init_test(struct kunit *test, const char *name, char *log);

int kunit_run_tests(struct kunit_suite *suite);
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 087fba34b209..30d343b4a40a 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -14,6 +14,12 @@ struct task_struct;
#include <linux/pgtable.h>
#include <asm/kasan.h>

+/* kasan_data struct is used in KUnit tests for KASAN expected failures */
+struct kunit_kasan_expectation {
+ bool report_expected;
+ bool report_found;
+};
+
extern unsigned char kasan_early_shadow_page[PAGE_SIZE];
extern pte_t kasan_early_shadow_pte[PTRS_PER_PTE];
extern pmd_t kasan_early_shadow_pmd[PTRS_PER_PMD];
diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index c36037200310..dcc35fd30d95 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -10,16 +10,12 @@
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/sched/debug.h>
+#include <linux/sched.h>

#include "debugfs.h"
#include "string-stream.h"
#include "try-catch-impl.h"

-static void kunit_set_failure(struct kunit *test)
-{
- WRITE_ONCE(test->success, false);
-}
-
static void kunit_print_tap_version(void)
{
static bool kunit_has_printed_tap_version;
@@ -288,6 +284,10 @@ static void kunit_try_run_case(void *data)
struct kunit_suite *suite = ctx->suite;
struct kunit_case *test_case = ctx->test_case;

+#if (IS_ENABLED(CONFIG_KASAN) && IS_ENABLED(CONFIG_KUNIT))
+ current->kunit_test = test;
+#endif /* IS_ENABLED(CONFIG_KASAN) && IS_ENABLED(CONFIG_KUNIT) */
+
/*
* kunit_run_case_internal may encounter a fatal error; if it does,
* abort will be called, this thread will exit, and finally the parent
@@ -602,6 +602,9 @@ void kunit_cleanup(struct kunit *test)
spin_unlock(&test->lock);
kunit_remove_resource(test, res);
}
+#if (IS_ENABLED(CONFIG_KASAN) && IS_ENABLED(CONFIG_KUNIT))
+ current->kunit_test = NULL;
+#endif /* IS_ENABLED(CONFIG_KASAN) && IS_ENABLED(CONFIG_KUNIT)*/
}
EXPORT_SYMBOL_GPL(kunit_cleanup);

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 53e953bb1d1d..58bffadd8367 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -23,6 +23,8 @@

#include <asm/page.h>

+#include <kunit/test.h>
+
#include "../mm/kasan/kasan.h"

#define OOB_TAG_OFF (IS_ENABLED(CONFIG_KASAN_GENERIC) ? 0 : KASAN_SHADOW_SCALE_SIZE)
@@ -32,14 +34,55 @@
* are not eliminated as dead code.
*/

-int kasan_int_result;
void *kasan_ptr_result;
+int kasan_int_result;
+
+static struct kunit_resource resource;
+static struct kunit_kasan_expectation fail_data;
+static bool multishot;
+
+static int kasan_test_init(struct kunit *test)
+{
+ /*
+ * Temporarily enable multi-shot mode and set panic_on_warn=0.
+ * Otherwise, we'd only get a report for the first case.
+ */
+ multishot = kasan_save_enable_multi_shot();
+
+ return 0;
+}
+
+static void kasan_test_exit(struct kunit *test)
+{
+ kasan_restore_multi_shot(multishot);
+}
+
+/**
+ * KUNIT_EXPECT_KASAN_FAIL() - Causes a test failure when the expression does
+ * not cause a KASAN error. This uses a KUnit resource named "kasan_data." Do
+ * Do not use this name for a KUnit resource outside here.
+ *
+ */
+#define KUNIT_EXPECT_KASAN_FAIL(test, condition) do { \
+ fail_data.report_expected = true; \
+ fail_data.report_found = false; \
+ kunit_add_named_resource(test, \
+ NULL, \
+ NULL, \
+ &resource, \
+ "kasan_data", &fail_data); \
+ condition; \
+ KUNIT_EXPECT_EQ(test, \
+ fail_data.report_expected, \
+ fail_data.report_found); \
+} while (0)
+
+

/*
* Note: test functions are marked noinline so that their names appear in
* reports.
*/
-
static noinline void __init kmalloc_oob_right(void)
{
char *ptr;
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 4f49fa6cd1aa..e2c14b10bc81 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -33,6 +33,8 @@

#include <asm/sections.h>

+#include <kunit/test.h>
+
#include "kasan.h"
#include "../slab.h"

@@ -464,12 +466,37 @@ static bool report_enabled(void)
return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags);
}

+#if IS_ENABLED(CONFIG_KUNIT)
+static void kasan_update_kunit_status(struct kunit *cur_test)
+{
+ struct kunit_resource *resource;
+ struct kunit_kasan_expectation *kasan_data;
+
+ resource = kunit_find_named_resource(cur_test, "kasan_data");
+
+ if (!resource) {
+ kunit_set_failure(cur_test);
+ return;
+ }
+
+ kasan_data = (struct kunit_kasan_expectation *)resource->data;
+ kasan_data->report_found = true;
+ kunit_put_resource(resource);
+}
+#endif /* IS_ENABLED(CONFIG_KUNIT) */
+
void kasan_report_invalid_free(void *object, unsigned long ip)
{
unsigned long flags;
u8 tag = get_tag(object);

object = reset_tag(object);
+
+#if IS_ENABLED(CONFIG_KUNIT)
+ if (current->kunit_test)
+ kasan_update_kunit_status(current->kunit_test);
+#endif /* IS_ENABLED(CONFIG_KUNIT) */
+
start_report(&flags);
pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip);
print_tags(tag, object);
@@ -488,6 +515,11 @@ static void __kasan_report(unsigned long addr, size_t size, bool is_write,
void *untagged_addr;
unsigned long flags;

+#if IS_ENABLED(CONFIG_KUNIT)
+ if (current->kunit_test)
+ kasan_update_kunit_status(current->kunit_test);
+#endif /* IS_ENABLED(CONFIG_KUNIT) */
+
disable_trace_on_warning();

tagged_addr = (void *)addr;
--
2.28.0.163.g6104cc2f0b6-goog