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@xxxxxxxxxx>
To: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
---
v2:
- added printk_test()
v4:
- test_kmsan: don't report -Wuninitialized warnings in the test
- test_kmsan.c: addressed comments by Andrey Konovalov
Change-Id: I287e86ae83a82b770f2baa46e5bbdce1dfa65195
---
lib/Makefile | 2 +
lib/test_kmsan.c | 229 +++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 231 insertions(+)
create mode 100644 lib/test_kmsan.c
diff --git a/lib/Makefile b/lib/Makefile
index ab68a86743607..d8058c5c05826 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -68,6 +68,8 @@ 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
+CFLAGS_test_kmsan.o += $(call cc-disable-warning, uninitialized)
obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o
obj-$(CONFIG_TEST_LIST_SORT) += test_list_sort.o
obj-$(CONFIG_TEST_MIN_HEAP) += test_min_heap.o
diff --git a/lib/test_kmsan.c b/lib/test_kmsan.c
new file mode 100644
index 0000000000000..f1780ed0cd315
--- /dev/null
+++ b/lib/test_kmsan.c
@@ -0,0 +1,229 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Module for testing KMSAN.
+ *
+ * Copyright (C) 2017-2019 Google LLC
+ * Author: Alexander Potapenko <glider@xxxxxxxxxx>
+ *
+ * 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)
+
+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);
+}
+
+noinline void params_test(void)
+{
+ volatile int uninit, init = 1;
+
+ pr_info("-----------------------------\n");
+ pr_info("uninit passed through a function parameter (UMR report)\n");
+ 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_test(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]);
+}
+
+noinline void printk_test(void)
+{
+ volatile int uninit;
+
+ pr_info("-----------------------------\n");
+ pr_info("uninit local passed to pr_info() (UMR report)\n");
+ pr_info("%px contains %d\n", &uninit, uninit);
+}
+
+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();
+ params_test();
+ uninit_kmsan_check_memory_test();
+ init_kmsan_vmap_vunmap_test();
+ init_vmalloc_test();
+ uaf_test();
+ printk_test();
+ return -EAGAIN;
+}
+
+module_init(kmsan_tests_init);
+MODULE_LICENSE("GPL");
--
2.25.1.696.g5e7596f4ac-goog
