[PATCH v5 2/4] KUnit: KASAN Integration

[David Gow]

From: Patricia Alfonso <trishalfonso@xxxxxxxxxx>

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
	- Also make KASAN no-longer panic when panic_on_warn and
	kasan_multi_shot are enabled (as multi-shot does nothing
	otherwise)

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@xxxxxxxxxx/T/#t)

Signed-off-by: Patricia Alfonso <trishalfonso@xxxxxxxxxx>
Signed-off-by: David Gow <davidgow@xxxxxxxxxx>
Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
---
 include/kunit/test.h  |  5 +++++
 include/linux/kasan.h |  6 ++++++
 lib/kunit/test.c      | 13 ++++++++-----
 lib/test_kasan.c      | 44 +++++++++++++++++++++++++++++++++++++++----
 mm/kasan/report.c     | 34 ++++++++++++++++++++++++++++++++-
 5 files changed, 92 insertions(+), 10 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..7b4cb107b387 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -23,12 +23,48 @@
 
 #include <asm/page.h>
 
-/*
- * Note: test functions are marked noinline so that their names appear in
- * reports.
+#include <kunit/test.h>
+
+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)
 
-static noinline void __init kmalloc_oob_right(void)
 {
 	char *ptr;
 	size_t size = 123;
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 5ef9f24f566b..a58a9f3b7f2c 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"
 
@@ -92,7 +94,7 @@ static void end_report(unsigned long *flags)
 	pr_err("==================================================================\n");
 	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 	spin_unlock_irqrestore(&report_lock, *flags);
-	if (panic_on_warn)
+	if (panic_on_warn && !test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
 		panic("panic_on_warn set ...\n");
 	kasan_enable_current();
 }
@@ -455,12 +457,37 @@ 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);
@@ -481,6 +508,11 @@ 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;
-- 
2.26.0.110.g2183baf09c-goog