Skip to content

Commit

Permalink
lib: add runtime test of check_*_overflow functions
Browse files Browse the repository at this point in the history 
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>
  • Loading branch information
Rasmus Villemoes authored and Kees Cook committed Jun 5, 2018
1 parent f090782 commit 455a35a
Show file tree
Hide file tree
Showing 3 changed files with 291 additions and 0 deletions.
3 changes: 3 additions & 0 deletions lib/Kconfig.debug
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down
1 change: 1 addition & 0 deletions lib/Makefile
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down
287 changes: 287 additions & 0 deletions lib/test_overflow.c
View file
Original file line number Diff line number Diff line change
@@ -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");

0 comments on commit 455a35a

Please sign in to comment.