lib: add runtime test of check_*_overflow functions

This adds a small module for testing that the check_*_overflow
functions work as expected, whether implemented in C or using gcc
builtins.

Example output:

test_overflow: u8 : 18 tests
test_overflow: s8 : 19 tests
test_overflow: u16: 17 tests
test_overflow: s16: 17 tests
test_overflow: u32: 17 tests
test_overflow: s32: 17 tests
test_overflow: u64: 17 tests
test_overflow: s64: 21 tests

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
[kees: add output to commit log, drop u64 tests on 32-bit]
Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index c40c7b734cd17efda88aa13c148cd56999684c8c..d9fe912afed57d6f0f986122f7f8c9ee79e03ed2 100644 (file)
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1785,6 +1785,9 @@ config TEST_BITMAP
 config TEST_UUID
        tristate "Test functions located in the uuid module at runtime"
 
+config TEST_OVERFLOW
+       tristate "Test check_*_overflow() functions at runtime"
+
 config TEST_RHASHTABLE
        tristate "Perform selftest on resizable hash table"
        default n

diff --git a/lib/Makefile b/lib/Makefile
index ce20696d5a92e7dcb0c22701fc83754ec77fe77d..eb762ad52ccf737c216e4f40c5a7b2ca633664d3 100644 (file)
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -59,6 +59,7 @@ UBSAN_SANITIZE_test_ubsan.o := y
 obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o
 obj-$(CONFIG_TEST_LIST_SORT) += test_list_sort.o
 obj-$(CONFIG_TEST_LKM) += test_module.o
+obj-$(CONFIG_TEST_OVERFLOW) += test_overflow.o
 obj-$(CONFIG_TEST_RHASHTABLE) += test_rhashtable.o
 obj-$(CONFIG_TEST_SORT) += test_sort.o
 obj-$(CONFIG_TEST_USER_COPY) += test_user_copy.o

diff --git a/lib/test_overflow.c b/lib/test_overflow.c
new file mode 100644 (file)
index 0000000..af01e46
--- /dev/null
+++ b/lib/test_overflow.c
@@ -0,0 +1,287 @@
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+/*
+ * Test cases for arithmetic overflow checks.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/overflow.h>
+#include <linux/types.h>
+
+#define DEFINE_TEST_ARRAY(t)                   \
+       static const struct test_ ## t {        \
+               t a, b;                         \
+               t sum, diff, prod;              \
+               bool s_of, d_of, p_of;          \
+       } t ## _tests[] __initconst
+
+DEFINE_TEST_ARRAY(u8) = {
+       {0, 0, 0, 0, 0, false, false, false},
+       {1, 1, 2, 0, 1, false, false, false},
+       {0, 1, 1, U8_MAX, 0, false, true, false},
+       {1, 0, 1, 1, 0, false, false, false},
+       {0, U8_MAX, U8_MAX, 1, 0, false, true, false},
+       {U8_MAX, 0, U8_MAX, U8_MAX, 0, false, false, false},
+       {1, U8_MAX, 0, 2, U8_MAX, true, true, false},
+       {U8_MAX, 1, 0, U8_MAX-1, U8_MAX, true, false, false},
+       {U8_MAX, U8_MAX, U8_MAX-1, 0, 1, true, false, true},
+
+       {U8_MAX, U8_MAX-1, U8_MAX-2, 1, 2, true, false, true},
+       {U8_MAX-1, U8_MAX, U8_MAX-2, U8_MAX, 2, true, true, true},
+
+       {1U << 3, 1U << 3, 1U << 4, 0, 1U << 6, false, false, false},
+       {1U << 4, 1U << 4, 1U << 5, 0, 0, false, false, true},
+       {1U << 4, 1U << 3, 3*(1U << 3), 1U << 3, 1U << 7, false, false, false},
+       {1U << 7, 1U << 7, 0, 0, 0, true, false, true},
+
+       {48, 32, 80, 16, 0, false, false, true},
+       {128, 128, 0, 0, 0, true, false, true},
+       {123, 234, 101, 145, 110, true, true, true},
+};
+DEFINE_TEST_ARRAY(u16) = {
+       {0, 0, 0, 0, 0, false, false, false},
+       {1, 1, 2, 0, 1, false, false, false},
+       {0, 1, 1, U16_MAX, 0, false, true, false},
+       {1, 0, 1, 1, 0, false, false, false},
+       {0, U16_MAX, U16_MAX, 1, 0, false, true, false},
+       {U16_MAX, 0, U16_MAX, U16_MAX, 0, false, false, false},
+       {1, U16_MAX, 0, 2, U16_MAX, true, true, false},
+       {U16_MAX, 1, 0, U16_MAX-1, U16_MAX, true, false, false},
+       {U16_MAX, U16_MAX, U16_MAX-1, 0, 1, true, false, true},
+
+       {U16_MAX, U16_MAX-1, U16_MAX-2, 1, 2, true, false, true},
+       {U16_MAX-1, U16_MAX, U16_MAX-2, U16_MAX, 2, true, true, true},
+
+       {1U << 7, 1U << 7, 1U << 8, 0, 1U << 14, false, false, false},
+       {1U << 8, 1U << 8, 1U << 9, 0, 0, false, false, true},
+       {1U << 8, 1U << 7, 3*(1U << 7), 1U << 7, 1U << 15, false, false, false},
+       {1U << 15, 1U << 15, 0, 0, 0, true, false, true},
+
+       {123, 234, 357, 65425, 28782, false, true, false},
+       {1234, 2345, 3579, 64425, 10146, false, true, true},
+};
+DEFINE_TEST_ARRAY(u32) = {
+       {0, 0, 0, 0, 0, false, false, false},
+       {1, 1, 2, 0, 1, false, false, false},
+       {0, 1, 1, U32_MAX, 0, false, true, false},
+       {1, 0, 1, 1, 0, false, false, false},
+       {0, U32_MAX, U32_MAX, 1, 0, false, true, false},
+       {U32_MAX, 0, U32_MAX, U32_MAX, 0, false, false, false},
+       {1, U32_MAX, 0, 2, U32_MAX, true, true, false},
+       {U32_MAX, 1, 0, U32_MAX-1, U32_MAX, true, false, false},
+       {U32_MAX, U32_MAX, U32_MAX-1, 0, 1, true, false, true},
+
+       {U32_MAX, U32_MAX-1, U32_MAX-2, 1, 2, true, false, true},
+       {U32_MAX-1, U32_MAX, U32_MAX-2, U32_MAX, 2, true, true, true},
+
+       {1U << 15, 1U << 15, 1U << 16, 0, 1U << 30, false, false, false},
+       {1U << 16, 1U << 16, 1U << 17, 0, 0, false, false, true},
+       {1U << 16, 1U << 15, 3*(1U << 15), 1U << 15, 1U << 31, false, false, false},
+       {1U << 31, 1U << 31, 0, 0, 0, true, false, true},
+
+       {-2U, 1U, -1U, -3U, -2U, false, false, false},
+       {-4U, 5U, 1U, -9U, -20U, true, false, true},
+};
+
+DEFINE_TEST_ARRAY(u64) = {
+       {0, 0, 0, 0, 0, false, false, false},
+       {1, 1, 2, 0, 1, false, false, false},
+       {0, 1, 1, U64_MAX, 0, false, true, false},
+       {1, 0, 1, 1, 0, false, false, false},
+       {0, U64_MAX, U64_MAX, 1, 0, false, true, false},
+       {U64_MAX, 0, U64_MAX, U64_MAX, 0, false, false, false},
+       {1, U64_MAX, 0, 2, U64_MAX, true, true, false},
+       {U64_MAX, 1, 0, U64_MAX-1, U64_MAX, true, false, false},
+       {U64_MAX, U64_MAX, U64_MAX-1, 0, 1, true, false, true},
+
+       {U64_MAX, U64_MAX-1, U64_MAX-2, 1, 2, true, false, true},
+       {U64_MAX-1, U64_MAX, U64_MAX-2, U64_MAX, 2, true, true, true},
+
+       {1ULL << 31, 1ULL << 31, 1ULL << 32, 0, 1ULL << 62, false, false, false},
+       {1ULL << 32, 1ULL << 32, 1ULL << 33, 0, 0, false, false, true},
+       {1ULL << 32, 1ULL << 31, 3*(1ULL << 31), 1ULL << 31, 1ULL << 63, false, false, false},
+       {1ULL << 63, 1ULL << 63, 0, 0, 0, true, false, true},
+       {1000000000ULL /* 10^9 */, 10000000000ULL /* 10^10 */,
+        11000000000ULL, 18446744064709551616ULL, 10000000000000000000ULL,
+        false, true, false},
+       {-15ULL, 10ULL, -5ULL, -25ULL, -150ULL, false, false, true},
+};
+
+DEFINE_TEST_ARRAY(s8) = {
+       {0, 0, 0, 0, 0, false, false, false},
+
+       {0, S8_MAX, S8_MAX, -S8_MAX, 0, false, false, false},
+       {S8_MAX, 0, S8_MAX, S8_MAX, 0, false, false, false},
+       {0, S8_MIN, S8_MIN, S8_MIN, 0, false, true, false},
+       {S8_MIN, 0, S8_MIN, S8_MIN, 0, false, false, false},
+
+       {-1, S8_MIN, S8_MAX, S8_MAX, S8_MIN, true, false, true},
+       {S8_MIN, -1, S8_MAX, -S8_MAX, S8_MIN, true, false, true},
+       {-1, S8_MAX, S8_MAX-1, S8_MIN, -S8_MAX, false, false, false},
+       {S8_MAX, -1, S8_MAX-1, S8_MIN, -S8_MAX, false, true, false},
+       {-1, -S8_MAX, S8_MIN, S8_MAX-1, S8_MAX, false, false, false},
+       {-S8_MAX, -1, S8_MIN, S8_MIN+2, S8_MAX, false, false, false},
+
+       {1, S8_MIN, -S8_MAX, -S8_MAX, S8_MIN, false, true, false},
+       {S8_MIN, 1, -S8_MAX, S8_MAX, S8_MIN, false, true, false},
+       {1, S8_MAX, S8_MIN, S8_MIN+2, S8_MAX, true, false, false},
+       {S8_MAX, 1, S8_MIN, S8_MAX-1, S8_MAX, true, false, false},
+
+       {S8_MIN, S8_MIN, 0, 0, 0, true, false, true},
+       {S8_MAX, S8_MAX, -2, 0, 1, true, false, true},
+
+       {-4, -32, -36, 28, -128, false, false, true},
+       {-4, 32, 28, -36, -128, false, false, false},
+};
+
+DEFINE_TEST_ARRAY(s16) = {
+       {0, 0, 0, 0, 0, false, false, false},
+
+       {0, S16_MAX, S16_MAX, -S16_MAX, 0, false, false, false},
+       {S16_MAX, 0, S16_MAX, S16_MAX, 0, false, false, false},
+       {0, S16_MIN, S16_MIN, S16_MIN, 0, false, true, false},
+       {S16_MIN, 0, S16_MIN, S16_MIN, 0, false, false, false},
+
+       {-1, S16_MIN, S16_MAX, S16_MAX, S16_MIN, true, false, true},
+       {S16_MIN, -1, S16_MAX, -S16_MAX, S16_MIN, true, false, true},
+       {-1, S16_MAX, S16_MAX-1, S16_MIN, -S16_MAX, false, false, false},
+       {S16_MAX, -1, S16_MAX-1, S16_MIN, -S16_MAX, false, true, false},
+       {-1, -S16_MAX, S16_MIN, S16_MAX-1, S16_MAX, false, false, false},
+       {-S16_MAX, -1, S16_MIN, S16_MIN+2, S16_MAX, false, false, false},
+
+       {1, S16_MIN, -S16_MAX, -S16_MAX, S16_MIN, false, true, false},
+       {S16_MIN, 1, -S16_MAX, S16_MAX, S16_MIN, false, true, false},
+       {1, S16_MAX, S16_MIN, S16_MIN+2, S16_MAX, true, false, false},
+       {S16_MAX, 1, S16_MIN, S16_MAX-1, S16_MAX, true, false, false},
+
+       {S16_MIN, S16_MIN, 0, 0, 0, true, false, true},
+       {S16_MAX, S16_MAX, -2, 0, 1, true, false, true},
+};
+DEFINE_TEST_ARRAY(s32) = {
+       {0, 0, 0, 0, 0, false, false, false},
+
+       {0, S32_MAX, S32_MAX, -S32_MAX, 0, false, false, false},
+       {S32_MAX, 0, S32_MAX, S32_MAX, 0, false, false, false},
+       {0, S32_MIN, S32_MIN, S32_MIN, 0, false, true, false},
+       {S32_MIN, 0, S32_MIN, S32_MIN, 0, false, false, false},
+
+       {-1, S32_MIN, S32_MAX, S32_MAX, S32_MIN, true, false, true},
+       {S32_MIN, -1, S32_MAX, -S32_MAX, S32_MIN, true, false, true},
+       {-1, S32_MAX, S32_MAX-1, S32_MIN, -S32_MAX, false, false, false},
+       {S32_MAX, -1, S32_MAX-1, S32_MIN, -S32_MAX, false, true, false},
+       {-1, -S32_MAX, S32_MIN, S32_MAX-1, S32_MAX, false, false, false},
+       {-S32_MAX, -1, S32_MIN, S32_MIN+2, S32_MAX, false, false, false},
+
+       {1, S32_MIN, -S32_MAX, -S32_MAX, S32_MIN, false, true, false},
+       {S32_MIN, 1, -S32_MAX, S32_MAX, S32_MIN, false, true, false},
+       {1, S32_MAX, S32_MIN, S32_MIN+2, S32_MAX, true, false, false},
+       {S32_MAX, 1, S32_MIN, S32_MAX-1, S32_MAX, true, false, false},
+
+       {S32_MIN, S32_MIN, 0, 0, 0, true, false, true},
+       {S32_MAX, S32_MAX, -2, 0, 1, true, false, true},
+};
+DEFINE_TEST_ARRAY(s64) = {
+       {0, 0, 0, 0, 0, false, false, false},
+
+       {0, S64_MAX, S64_MAX, -S64_MAX, 0, false, false, false},
+       {S64_MAX, 0, S64_MAX, S64_MAX, 0, false, false, false},
+       {0, S64_MIN, S64_MIN, S64_MIN, 0, false, true, false},
+       {S64_MIN, 0, S64_MIN, S64_MIN, 0, false, false, false},
+
+       {-1, S64_MIN, S64_MAX, S64_MAX, S64_MIN, true, false, true},
+       {S64_MIN, -1, S64_MAX, -S64_MAX, S64_MIN, true, false, true},
+       {-1, S64_MAX, S64_MAX-1, S64_MIN, -S64_MAX, false, false, false},
+       {S64_MAX, -1, S64_MAX-1, S64_MIN, -S64_MAX, false, true, false},
+       {-1, -S64_MAX, S64_MIN, S64_MAX-1, S64_MAX, false, false, false},
+       {-S64_MAX, -1, S64_MIN, S64_MIN+2, S64_MAX, false, false, false},
+
+       {1, S64_MIN, -S64_MAX, -S64_MAX, S64_MIN, false, true, false},
+       {S64_MIN, 1, -S64_MAX, S64_MAX, S64_MIN, false, true, false},
+       {1, S64_MAX, S64_MIN, S64_MIN+2, S64_MAX, true, false, false},
+       {S64_MAX, 1, S64_MIN, S64_MAX-1, S64_MAX, true, false, false},
+
+       {S64_MIN, S64_MIN, 0, 0, 0, true, false, true},
+       {S64_MAX, S64_MAX, -2, 0, 1, true, false, true},
+
+       {-1, -1, -2, 0, 1, false, false, false},
+       {-1, -128, -129, 127, 128, false, false, false},
+       {-128, -1, -129, -127, 128, false, false, false},
+       {0, -S64_MAX, -S64_MAX, S64_MAX, 0, false, false, false},
+};
+
+#define DEFINE_TEST_FUNC(t, fmt)                                       \
+static void __init do_test_ ## t(const struct test_ ## t *p)           \
+{                                                                      \
+       t r;                                                            \
+       bool of;                                                        \
+                                                                       \
+       of = check_add_overflow(p->a, p->b, &r);                        \
+       if (of != p->s_of)                                              \
+               pr_warn("expected "fmt" + "fmt" to%s overflow (type %s)\n", \
+                       p->a, p->b, p->s_of ? "" : " not", #t);         \
+       if (r != p->sum)                                                \
+               pr_warn("expected "fmt" + "fmt" == "fmt", got "fmt" (type %s)\n", \
+                       p->a, p->b, p->sum, r, #t);                     \
+                                                                       \
+       of = check_sub_overflow(p->a, p->b, &r);                        \
+       if (of != p->d_of)                                              \
+               pr_warn("expected "fmt" - "fmt" to%s overflow (type %s)\n", \
+                       p->a, p->b, p->s_of ? "" : " not", #t);         \
+       if (r != p->diff)                                               \
+               pr_warn("expected "fmt" - "fmt" == "fmt", got "fmt" (type %s)\n", \
+                       p->a, p->b, p->diff, r, #t);                    \
+                                                                       \
+       of = check_mul_overflow(p->a, p->b, &r);                        \
+       if (of != p->p_of)                                              \
+               pr_warn("expected "fmt" * "fmt" to%s overflow (type %s)\n", \
+                       p->a, p->b, p->p_of ? "" : " not", #t);         \
+       if (r != p->prod)                                               \
+               pr_warn("expected "fmt" * "fmt" == "fmt", got "fmt" (type %s)\n", \
+                       p->a, p->b, p->prod, r, #t);                    \
+}                                                                      \
+                                                                       \
+static void __init test_ ## t ## _overflow(void) {                     \
+       unsigned i;                                                     \
+                                                                       \
+       pr_info("%-3s: %zu tests\n", #t, ARRAY_SIZE(t ## _tests));      \
+       for (i = 0; i < ARRAY_SIZE(t ## _tests); ++i)                   \
+               do_test_ ## t(&t ## _tests[i]);                         \
+}
+
+DEFINE_TEST_FUNC(u8, "%d");
+DEFINE_TEST_FUNC(s8, "%d");
+DEFINE_TEST_FUNC(u16, "%d");
+DEFINE_TEST_FUNC(s16, "%d");
+DEFINE_TEST_FUNC(u32, "%u");
+DEFINE_TEST_FUNC(s32, "%d");
+#if BITS_PER_LONG == 64
+DEFINE_TEST_FUNC(u64, "%llu");
+DEFINE_TEST_FUNC(s64, "%lld");
+#endif
+
+static int __init test_overflow(void)
+{
+       test_u8_overflow();
+       test_s8_overflow();
+       test_u16_overflow();
+       test_s16_overflow();
+       test_u32_overflow();
+       test_s32_overflow();
+#if BITS_PER_LONG == 64
+       test_u64_overflow();
+       test_s64_overflow();
+#endif
+
+       pr_info("done\n");
+
+       return 0;
+}
+
+static void __exit test_module_exit(void)
+{ }
+
+module_init(test_overflow);
+module_exit(test_module_exit);
+MODULE_LICENSE("Dual MIT/GPL");