kasan: fail non-kasan KUnit tests on KASAN reports

After the recent changes done to KUnit-enabled KASAN tests, non-KASAN KUnit
tests stopped being failed when KASAN report is detected.

Recover that property by failing the currently running non-KASAN KUnit test
when KASAN detects and prints a report for a bad memory access.

Note that if the bad accesses happened in a kernel thread that doesn't
have a reference to the currently running KUnit-test available via
current->kunit_test, the test won't be failed. This is a limitation of
KUnit, which doesn't yet provide a thread-agnostic way to find the
reference to the currenly running test.

Fixes: 49d9977 ("kasan: check CONFIG_KASAN_KUNIT_TEST instead of CONFIG_KUNIT")
Fixes: 7f29493ba529 ("kasan: switch kunit tests to console tracepoints")
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

mm/kasan/kasan.h

@@ -563,6 +563,12 @@ void kasan_restore_multi_shot(bool enabled);
 
 #endif
 
+#if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
+bool kasan_kunit_test_suite_executing(void);
+#else
+static bool kasan_kunit_test_suite_executing(void) { return false; }
+#endif
+
 /*
  * Exported functions for interfaces called from assembly or from generated
  * code. Declared here to avoid warnings about missing declarations.

mm/kasan/kasan_test.c

@@ -32,6 +32,9 @@
 
 #define OOB_TAG_OFF (IS_ENABLED(CONFIG_KASAN_GENERIC) ? 0 : KASAN_GRANULE_SIZE)
 
+/* Whether the KASAN KUnit test suite is currently being executed. */
+static bool executing;
+
 static bool multishot;
 
 /* Fields set based on lines observed in the console. */
@@ -47,6 +50,11 @@ static struct {
 void *kasan_ptr_result;
 int kasan_int_result;
 
+bool kasan_kunit_test_suite_executing(void)
+{
+	return READ_ONCE(executing);
+}
+
 /* Probe for console output: obtains test_status lines of interest. */
 static void probe_console(void *ignore, const char *buf, size_t len)
 {
@@ -76,6 +84,8 @@ static int kasan_suite_init(struct kunit_suite *suite)
 		return -1;
 	}
 
+	WRITE_ONCE(executing, true);
+
 	/*
 	 * Temporarily enable multi-shot mode. Otherwise, KASAN would only
 	 * report the first detected bug and panic the kernel if panic_on_warn
@@ -94,6 +104,7 @@ static int kasan_suite_init(struct kunit_suite *suite)
 
 static void kasan_suite_exit(struct kunit_suite *suite)
 {
+	WRITE_ONCE(executing, false);
 	kasan_restore_multi_shot(multishot);
 	for_each_kernel_tracepoint(unregister_tracepoints, NULL);
 	tracepoint_synchronize_unregister();

mm/kasan/report.c

@@ -9,6 +9,7 @@
  *        Andrey Konovalov <andreyknvl@gmail.com>
  */
 
+#include <kunit/test.h>
 #include <linux/bitops.h>
 #include <linux/ftrace.h>
 #include <linux/init.h>
@@ -112,10 +113,31 @@ EXPORT_SYMBOL_GPL(kasan_restore_multi_shot);
 
 #endif
 
+#if IS_ENABLED(CONFIG_KUNIT)
+
+static void fail_nonkasan_kunit_test(void)
+{
+	struct kunit *test;
+
+	if (!kasan_kunit_test_suite_executing())
+		return;
+
+	test = current->kunit_test;
+	if (test)
+		kunit_set_failure(test);
+}
+
+#else /* CONFIG_KUNIT */
+
+static void fail_nonkasan_kunit_test(void) { }
+
+#endif /* CONFIG_KUNIT */
+
 static DEFINE_SPINLOCK(report_lock);
 
 static void start_report(unsigned long *flags, bool sync)
 {
+	fail_nonkasan_kunit_test();
 	/* Respect the /proc/sys/kernel/traceoff_on_warning interface. */
 	disable_trace_on_warning();
 	/* Do not allow LOCKDEP mangling KASAN reports. */