[PATCH RFC v1 13/26] kmsan: add tests for KMSAN

[glider@google.com]

The initial commit adds several tests that trigger KMSAN warnings in
simple cases.
To use, build the kernel with CONFIG_TEST_KMSAN and do
`insmod test_kmsan.ko`

Signed-off-by: Alexander Potapenko <glider@google.com>
To: Alexander Potapenko <glider@google.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: linux-mm@kvack.org
---

Change-Id: I287e86ae83a82b770f2baa46e5bbdce1dfa65195
---
 lib/Makefile     |   1 +
 lib/test_kmsan.c | 221 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 222 insertions(+)
 create mode 100644 lib/test_kmsan.c

diff --git a/lib/Makefile b/lib/Makefile
index c5892807e06f..cb44262c38ee 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -65,6 +65,7 @@ CFLAGS_test_kasan.o += $(call cc-disable-warning, vla)
 obj-$(CONFIG_TEST_UBSAN) += test_ubsan.o
 CFLAGS_test_ubsan.o += $(call cc-disable-warning, vla)
 UBSAN_SANITIZE_test_ubsan.o := y
+obj-$(CONFIG_TEST_KMSAN) += test_kmsan.o
 obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o
 obj-$(CONFIG_TEST_LIST_SORT) += test_list_sort.o
 obj-$(CONFIG_TEST_LKM) += test_module.o
diff --git a/lib/test_kmsan.c b/lib/test_kmsan.c
new file mode 100644
index 000000000000..97051444c6c4
--- /dev/null
+++ b/lib/test_kmsan.c
@@ -0,0 +1,221 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Module for testing KMSAN.
+ *
+ * Copyright (C) 2017-2019 Google LLC
+ * Author: Alexander Potapenko <glider@google.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+/*
+ * Tests below use noinline and volatile to work around compiler optimizations
+ * that may mask KMSAN bugs.
+ */
+#define pr_fmt(fmt) "kmsan test: %s : " fmt, __func__
+
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/slab.h>
+#include <linux/kmsan-checks.h>
+
+#define CHECK(x)					\
+	do {						\
+		if (x)					\
+			pr_info(#x " is true\n");	\
+		else					\
+			pr_info(#x " is false\n");	\
+	} while (0)
+
+noinline void use_integer(int cond)
+{
+	CHECK(cond);
+}
+
+int signed_sum3(int a, int b, int c)
+{
+	return a + b + c;
+}
+
+noinline void uninit_kmalloc_test(void)
+{
+	int *ptr;
+
+	pr_info("-----------------------------\n");
+	pr_info("uninitialized kmalloc test (UMR report)\n");
+	ptr = kmalloc(sizeof(int), GFP_KERNEL);
+	pr_info("kmalloc returned %p\n", ptr);
+	CHECK(*ptr);
+}
+noinline void init_kmalloc_test(void)
+{
+	int *ptr;
+
+	pr_info("-----------------------------\n");
+	pr_info("initialized kmalloc test (no reports)\n");
+	ptr = kmalloc(sizeof(int), GFP_KERNEL);
+	memset(ptr, 0, sizeof(int));
+	pr_info("kmalloc returned %p\n", ptr);
+	CHECK(*ptr);
+}
+
+noinline void init_kzalloc_test(void)
+{
+	int *ptr;
+
+	pr_info("-----------------------------\n");
+	pr_info("initialized kzalloc test (no reports)\n");
+	ptr = kzalloc(sizeof(int), GFP_KERNEL);
+	pr_info("kzalloc returned %p\n", ptr);
+	CHECK(*ptr);
+}
+
+noinline void uninit_multiple_args_test(void)
+{
+	volatile int a;
+	volatile char b = 3, c;
+
+	pr_info("-----------------------------\n");
+	pr_info("uninitialized local passed to fn (UMR report)\n");
+	CHECK(signed_sum3(a, b, c));
+}
+
+noinline void uninit_stack_var_test(void)
+{
+	int cond;
+
+	pr_info("-----------------------------\n");
+	pr_info("uninitialized stack variable (UMR report)\n");
+	CHECK(cond);
+}
+
+noinline void init_stack_var_test(void)
+{
+	volatile int cond = 1;
+
+	pr_info("-----------------------------\n");
+	pr_info("initialized stack variable (no reports)\n");
+	CHECK(cond);
+}
+
+noinline void two_param_fn_2(int arg1, int arg2)
+{
+	CHECK(arg1);
+	CHECK(arg2);
+}
+
+noinline void one_param_fn(int arg)
+{
+	two_param_fn_2(arg, arg);
+	CHECK(arg);
+}
+
+noinline void two_param_fn(int arg1, int arg2)
+{
+	int init = 0;
+
+	one_param_fn(init);
+	CHECK(arg1);
+	CHECK(arg2);
+}
+
+void params_test(void)
+{
+	int uninit, init = 1;
+
+	two_param_fn(uninit, init);
+}
+
+noinline void do_uninit_local_array(char *array, int start, int stop)
+{
+	int i;
+	volatile char uninit;
+
+	for (i = start; i < stop; i++)
+		array[i] = uninit;
+}
+
+noinline void uninit_kmsan_check_memory_test(void)
+{
+	volatile char local_array[8];
+
+	pr_info("-----------------------------\n");
+	pr_info("kmsan_check_memory() called on uninit local (UMR report)\n");
+	do_uninit_local_array((char *)local_array, 5, 7);
+
+	kmsan_check_memory((char *)local_array, 8);
+}
+
+noinline void init_kmsan_vmap_vunmap_test(void)
+{
+	const int npages = 2;
+	struct page *pages[npages];
+	void *vbuf;
+	int i;
+
+	pr_info("-----------------------------\n");
+	pr_info("pages initialized via vmap (no reports)\n");
+
+	for (i = 0; i < npages; i++)
+		pages[i] = alloc_page(GFP_KERNEL);
+	vbuf = vmap(pages, npages, VM_MAP, PAGE_KERNEL);
+	memset(vbuf, 0xfe, npages * PAGE_SIZE);
+	for (i = 0; i < npages; i++)
+		kmsan_check_memory(page_address(pages[i]), PAGE_SIZE);
+
+	if (vbuf)
+		vunmap(vbuf);
+	for (i = 0; i < npages; i++)
+		if (pages[i])
+			__free_page(pages[i]);
+}
+
+noinline void init_vmalloc(void)
+{
+	char *buf;
+	int npages = 8, i;
+
+	pr_info("-----------------------------\n");
+	pr_info("pages initialized via vmap (no reports)\n");
+	buf = vmalloc(PAGE_SIZE * npages);
+	buf[0] = 1;
+	memset(buf, 0xfe, PAGE_SIZE * npages);
+	CHECK(buf[0]);
+	for (i = 0; i < npages; i++)
+		kmsan_check_memory(&buf[PAGE_SIZE * i], PAGE_SIZE);
+	vfree(buf);
+}
+
+noinline void uaf_test(void)
+{
+	volatile int *var;
+
+	pr_info("-----------------------------\n");
+	pr_info("use-after-free in kmalloc-ed buffer (UMR report)\n");
+	var = kmalloc(80, GFP_KERNEL);
+	var[3] = 0xfeedface;
+	kfree((int *)var);
+	CHECK(var[3]);
+}
+
+static noinline int __init kmsan_tests_init(void)
+{
+	uninit_kmalloc_test();
+	init_kmalloc_test();
+	init_kzalloc_test();
+	uninit_multiple_args_test();
+	uninit_stack_var_test();
+	init_stack_var_test();
+	uninit_kmsan_check_memory_test();
+	init_kmsan_vmap_vunmap_test();
+	init_vmalloc();
+	uaf_test();
+	return -EAGAIN;
+}
+
+module_init(kmsan_tests_init);
+MODULE_LICENSE("GPL");
-- 
2.23.0.866.gb869b98d4c-goog