Re: [PATCH v3 2/4] KUnit: KASAN Integration

On Wed, Apr 1, 2020 at 8:09 PM 'Patricia Alfonso' via kasan-dev kasan-dev@googlegroups.com wrote:

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-al...)

Signed-off-by: Patricia Alfonso trishalfonso@google.com

include/kunit/test.h | 5 +++++ include/linux/kasan.h | 6 ++++++ lib/kunit/test.c | 13 ++++++++----- lib/test_kasan.c | 37 +++++++++++++++++++++++++++++++++++++ mm/kasan/report.c | 33 +++++++++++++++++++++++++++++++++ 5 files changed, 89 insertions(+), 5 deletions(-)

diff --git a/include/kunit/test.h b/include/kunit/test.h index ac59d18e6bab..1dc3d118f64b 100644 --- a/include/kunit/test.h +++ b/include/kunit/test.h @@ -225,6 +225,11 @@ 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 5cde9e7c2664..148eaef3e003 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -14,6 +14,12 @@ struct task_struct; #include <asm/kasan.h> #include <asm/pgtable.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 2cb7c6220a00..030a3281591e 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
  

@@ -603,6 +603,9 @@ 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 3872d250ed2c..cf73c6bee81b 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -23,6 +23,43 @@

#include <asm/page.h>

+#include <kunit/test.h>

+struct kunit_resource resource; +struct kunit_kasan_expectation fail_data;

+#define KUNIT_SET_KASAN_DATA(test) do { \

•   fail_data.report_expected = true; \
  

•   fail_data.report_found = false; \
  

•   kunit_add_named_resource(test, \
  

•                           NULL, \
  

•                           NULL, \
  

•                           &resource, \
  

•                           "kasan_data", &fail_data); \
  

+} while (0)

+#define KUNIT_DO_EXPECT_KASAN_FAIL(test, condition) do { \

•   struct kunit_resource *resource; \
  

•   struct kunit_kasan_expectation *kasan_data; \
  

•   condition; \
  

•   resource = kunit_find_named_resource(test, "kasan_data"); \
  

•   kasan_data = resource->data; \
  

•   KUNIT_EXPECT_EQ(test, \
  

•                   kasan_data->report_expected, \
  

•                   kasan_data->report_found); \
  

•   kunit_put_resource(resource); \
  

+} while (0)

+/**

• • KUNIT_EXPECT_KASAN_FAIL() - Causes a test failure when the expression does
• • not cause a KASAN error.
• */

+#define KUNIT_EXPECT_KASAN_FAIL(test, condition) do { \

•   KUNIT_SET_KASAN_DATA(test); \
  

•   KUNIT_DO_EXPECT_KASAN_FAIL(test, condition); \
  

+} while (0)

Any reason to split this macro into two parts? Do we call any of them separately?

/*

• Note: test functions are marked noinline so that their names appear in
• reports.

diff --git a/mm/kasan/report.c b/mm/kasan/report.c index 5ef9f24f566b..87330ef3a99a 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -32,6 +32,8 @@

#include <asm/sections.h>

+#include <kunit/test.h>

#include "kasan.h" #include "../slab.h"

@@ -455,12 +457,38 @@ static bool report_enabled(void) return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags); }

+#if IS_ENABLED(CONFIG_KUNIT) +void kasan_update_kunit_status(struct kunit *cur_test) +{

•   struct kunit_resource *resource;
  

•   struct kunit_kasan_expectation *kasan_data;
  

•   if (kunit_find_named_resource(cur_test, "kasan_data")) {
  

•           resource = kunit_find_named_resource(cur_test, "kasan_data");
  

•           kasan_data = resource->data;
  

•           kasan_data->report_found = true;
  

•           if (!kasan_data->report_expected)
  

•                   kunit_set_failure(current->kunit_test);
  

Hm, we only call KUNIT_SET_KASAN_DATA() for KASAN tests that we expect to fail AFAICS. Then we end up calling kunit_set_failure twice, once here and the other time when we do KUNIT_EXPECT_EQ() in KUNIT_DO_EXPECT_KASAN_FAIL(). Or maybe there's something I misunderstand.

•           else
  

•                   return;
  

Nit: "else return;" can be dropped.

You can actually reorder the code a bit to make it easier to read:

if (!kunit_find_named_resource(cur_test, "kasan_data")) { kunit_set_failure(current->kunit_test); return; } // here comes kasan tests checks

•   } else
  

•           kunit_set_failure(current->kunit_test);
  

+} +#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);
  

@@ -481,6 +509,11 @@ void __kasan_report(unsigned long addr, size_t size, bool is_write, unsigned lon if (likely(!report_enabled())) return;

+#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;
  

-- 2.26.0.rc2.310.g2932bb562d-goog

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