kunit/overflow: Fix UB in overflow_allocation_test

The 'device_name' array doesn't exist out of the
'overflow_allocation_test' function scope. However, it is being used as
a driver name when calling 'kunit_driver_create' from
'kunit_device_register'. It produces the kernel panic with KASAN
enabled.

Since this variable is used in one place only, remove it and pass the
device name into kunit_device_register directly as an ascii string.
Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Reviewed-by: David Gow <davidgow@google.com>
Link: https://lore.kernel.org/r/20240815000431.401869-1-ivan.orlov0322@gmail.comSigned-off-by: Kees Cook <kees@kernel.org>

lib/overflow_kunit.c

@@ -668,7 +668,6 @@ DEFINE_TEST_ALLOC(devm_kzalloc,  devm_kfree, 1, 1, 0);
 
 static void overflow_allocation_test(struct kunit *test)
 {
-	const char device_name[] = "overflow-test";
 	struct device *dev;
 	int count = 0;
 
@@ -678,7 +677,7 @@ static void overflow_allocation_test(struct kunit *test)
 } while (0)
 
 	/* Create dummy device for devm_kmalloc()-family tests. */
-	dev = kunit_device_register(test, device_name);
+	dev = kunit_device_register(test, "overflow-test");
 	KUNIT_ASSERT_FALSE_MSG(test, IS_ERR(dev),
 			       "Cannot register test device\n");