Re: [RFC PATCH v2 2/3] KUnit: KASAN Integration

On Tue, Mar 24, 2020 at 9:45 AM Alan Maguire alan.maguire@oracle.com wrote:

On Thu, 19 Mar 2020, Patricia Alfonso 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 "[RFC PATCH kunit-next 1/2] kunit: generalize kunit_resource API beyond allocated resources" and "[RFC PATCH 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 | 10 ++++++++++ lib/kunit/test.c | 10 +++++++++- lib/test_kasan.c | 37 +++++++++++++++++++++++++++++++++++++ mm/kasan/report.c | 33 +++++++++++++++++++++++++++++++++ 4 files changed, 89 insertions(+), 1 deletion(-)

diff --git a/include/kunit/test.h b/include/kunit/test.h index 70ee581b19cd..2ab265f4f76c 100644 --- a/include/kunit/test.h +++ b/include/kunit/test.h @@ -19,9 +19,19 @@

struct kunit_resource;

+#ifdef CONFIG_KASAN +/* kasan_data struct is used in KUnit tests for KASAN expected failures */ +struct kunit_kasan_expectation {

• bool report_expected;
  

• bool report_found;
  

+}; +#endif /* CONFIG_KASAN */

Above should be moved to mm/kasan/kasan.h I think.

...

typedef int (*kunit_resource_init_t)(struct kunit_resource *, void *); typedef void (*kunit_resource_free_t)(struct kunit_resource *);

+void kunit_set_failure(struct kunit *test);

Can you explain a bit more about why we need this exported? I see where it's used but I'd just like to make sure I understand what you're trying to do. Thanks!

I need the ability to set a KUnit test failure from outside the KUnit code so that a test that does not expect a KASAN failure, but reaches the point in the KASAN code where a report is printed will properly fail due to this found KASAN failure.

...

/**

• struct kunit_resource - represents a *test managed resource*
• @data: for the user to store arbitrary data.

diff --git a/lib/kunit/test.c b/lib/kunit/test.c index 86a4d9ca0a45..3f927ef45827 100644 --- a/lib/kunit/test.c +++ b/lib/kunit/test.c @@ -10,11 +10,12 @@ #include <linux/kernel.h> #include <linux/kref.h> #include <linux/sched/debug.h> +#include <linux/sched.h>

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

-static void kunit_set_failure(struct kunit *test) +void kunit_set_failure(struct kunit *test) { WRITE_ONCE(test->success, false); } @@ -237,6 +238,10 @@ 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_BUILTIN(CONFIG_KUNIT))

• current->kunit_test = test;
  

+#endif /* IS_ENABLED(CONFIG_KASAN) && IS_BUILTIN(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
  

@@ -590,6 +595,9 @@ void kunit_cleanup(struct kunit *test) spin_unlock(&test->lock); kunit_remove_resource(test, res); } +#if (IS_ENABLED(CONFIG_KASAN) && IS_BUILTIN(CONFIG_KUNIT))

• current->kunit_test = NULL;
  

As per patch 1, I'd suggest changing here and elsewhere to "IS_ENABLED(CONFIG_KUNIT)".

"IS_ENABLED(CONFIG_KUNIT)" does not work because KASAN is built-in so it can't rely on modules so this patchset relies on KUnit being built-in.

...

+#endif /* IS_ENABLED(CONFIG_KASAN) && IS_BUILTIN(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)

/*

• 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..ef3d0f54097e 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_BUILTIN(CONFIG_KUNIT)

again we could tweak this to IS_ENABLED(CONFIG_KUNIT); BTW the reason we can compile kunit as a module for these tests is the KASAN tests are tristate themselves. If they were builtin only it wouldn't be possible to build kunit as a module.

...

+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);
  

•         else
  

•                 return;
  

• } else
  

•         kunit_set_failure(current->kunit_test);
  

+} +#endif /* IS_BUILTIN(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_BUILTIN(CONFIG_KUNIT)

same comment as above.

...

• if (current->kunit_test)
  

•         kasan_update_kunit_status(current->kunit_test);
  

+#endif /* IS_BUILTIN(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_BUILTIN(CONFIG_KUNIT)

here too.

...

• if (current->kunit_test)
  

•         kasan_update_kunit_status(current->kunit_test);
  

+#endif /* IS_BUILTIN(CONFIG_KUNIT) */

• disable_trace_on_warning();
  
  tagged_addr = (void *)addr;
  

-- 2.25.1.696.g5e7596f4ac-goog