linux/lib/test_stackinit.c
Masahiro Yamada 8e82fe2ab6 treewide: fix typos of SPDX-License-Identifier
Prior to the adoption of SPDX, it was difficult for tools to determine
the correct license due to incomplete or badly formatted license text.
The SPDX solves this issue, assuming people can correctly spell
"SPDX-License-Identifier" although this assumption is broken in some
places.

Since scripts/spdxcheck.py parses only lines that exactly matches to
the correct tag, it cannot (should not) detect this kind of error.

If the correct tag is missing, scripts/checkpatch.pl warns like this:

 WARNING: Missing or malformed SPDX-License-Identifier tag in line *

So, people should notice it before the patch submission, but in reality
broken tags sometimes slip in. The checkpatch warning is not useful for
checking the committed files globally since large number of files still
have no SPDX tag.

Also, I am not sure about the legal effect when the SPDX tag is broken.

Anyway, these typos are absolutely worth fixing. It is pretty easy to
find suspicious lines by grep.

  $ git grep --not -e SPDX-License-Identifier --and -e SPDX- -- \
    :^LICENSES :^scripts/spdxcheck.py :^*/license-rules.rst
  arch/arm/kernel/bugs.c:// SPDX-Identifier: GPL-2.0
  drivers/phy/st/phy-stm32-usbphyc.c:// SPDX-Licence-Identifier: GPL-2.0
  drivers/pinctrl/sh-pfc/pfc-r8a77980.c:// SPDX-Lincense-Identifier: GPL 2.0
  lib/test_stackinit.c:// SPDX-Licenses: GPLv2
  sound/soc/codecs/max9759.c:// SPDX-Licence-Identifier: GPL-2.0

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-01 18:29:58 +02:00

379 lines
11 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Test cases for compiler-based stack variable zeroing via future
* compiler flags or CONFIG_GCC_PLUGIN_STRUCTLEAK*.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/string.h>
/* Exfiltration buffer. */
#define MAX_VAR_SIZE 128
static char check_buf[MAX_VAR_SIZE];
/* Character array to trigger stack protector in all functions. */
#define VAR_BUFFER 32
/* Volatile mask to convince compiler to copy memory with 0xff. */
static volatile u8 forced_mask = 0xff;
/* Location and size tracking to validate fill and test are colocated. */
static void *fill_start, *target_start;
static size_t fill_size, target_size;
static bool range_contains(char *haystack_start, size_t haystack_size,
char *needle_start, size_t needle_size)
{
if (needle_start >= haystack_start &&
needle_start + needle_size <= haystack_start + haystack_size)
return true;
return false;
}
#define DO_NOTHING_TYPE_SCALAR(var_type) var_type
#define DO_NOTHING_TYPE_STRING(var_type) void
#define DO_NOTHING_TYPE_STRUCT(var_type) void
#define DO_NOTHING_RETURN_SCALAR(ptr) *(ptr)
#define DO_NOTHING_RETURN_STRING(ptr) /**/
#define DO_NOTHING_RETURN_STRUCT(ptr) /**/
#define DO_NOTHING_CALL_SCALAR(var, name) \
(var) = do_nothing_ ## name(&(var))
#define DO_NOTHING_CALL_STRING(var, name) \
do_nothing_ ## name(var)
#define DO_NOTHING_CALL_STRUCT(var, name) \
do_nothing_ ## name(&(var))
#define FETCH_ARG_SCALAR(var) &var
#define FETCH_ARG_STRING(var) var
#define FETCH_ARG_STRUCT(var) &var
#define FILL_SIZE_STRING 16
#define INIT_CLONE_SCALAR /**/
#define INIT_CLONE_STRING [FILL_SIZE_STRING]
#define INIT_CLONE_STRUCT /**/
#define INIT_SCALAR_none /**/
#define INIT_SCALAR_zero = 0
#define INIT_STRING_none [FILL_SIZE_STRING] /**/
#define INIT_STRING_zero [FILL_SIZE_STRING] = { }
#define INIT_STRUCT_none /**/
#define INIT_STRUCT_zero = { }
#define INIT_STRUCT_static_partial = { .two = 0, }
#define INIT_STRUCT_static_all = { .one = arg->one, \
.two = arg->two, \
.three = arg->three, \
.four = arg->four, \
}
#define INIT_STRUCT_dynamic_partial = { .two = arg->two, }
#define INIT_STRUCT_dynamic_all = { .one = arg->one, \
.two = arg->two, \
.three = arg->three, \
.four = arg->four, \
}
#define INIT_STRUCT_runtime_partial ; \
var.two = 0
#define INIT_STRUCT_runtime_all ; \
var.one = 0; \
var.two = 0; \
var.three = 0; \
memset(&var.four, 0, \
sizeof(var.four))
/*
* @name: unique string name for the test
* @var_type: type to be tested for zeroing initialization
* @which: is this a SCALAR, STRING, or STRUCT type?
* @init_level: what kind of initialization is performed
*/
#define DEFINE_TEST_DRIVER(name, var_type, which) \
/* Returns 0 on success, 1 on failure. */ \
static noinline __init int test_ ## name (void) \
{ \
var_type zero INIT_CLONE_ ## which; \
int ignored; \
u8 sum = 0, i; \
\
/* Notice when a new test is larger than expected. */ \
BUILD_BUG_ON(sizeof(zero) > MAX_VAR_SIZE); \
\
/* Fill clone type with zero for per-field init. */ \
memset(&zero, 0x00, sizeof(zero)); \
/* Fill stack with 0xFF. */ \
ignored = leaf_ ##name((unsigned long)&ignored, 1, \
FETCH_ARG_ ## which(zero)); \
/* Clear entire check buffer for later bit tests. */ \
memset(check_buf, 0x00, sizeof(check_buf)); \
/* Extract stack-defined variable contents. */ \
ignored = leaf_ ##name((unsigned long)&ignored, 0, \
FETCH_ARG_ ## which(zero)); \
\
/* Validate that compiler lined up fill and target. */ \
if (!range_contains(fill_start, fill_size, \
target_start, target_size)) { \
pr_err(#name ": stack fill missed target!?\n"); \
pr_err(#name ": fill %zu wide\n", fill_size); \
pr_err(#name ": target offset by %d\n", \
(int)((ssize_t)(uintptr_t)fill_start - \
(ssize_t)(uintptr_t)target_start)); \
return 1; \
} \
\
/* Look for any set bits in the check region. */ \
for (i = 0; i < sizeof(check_buf); i++) \
sum += (check_buf[i] != 0); \
\
if (sum == 0) \
pr_info(#name " ok\n"); \
else \
pr_warn(#name " FAIL (uninit bytes: %d)\n", \
sum); \
\
return (sum != 0); \
}
#define DEFINE_TEST(name, var_type, which, init_level) \
/* no-op to force compiler into ignoring "uninitialized" vars */\
static noinline __init DO_NOTHING_TYPE_ ## which(var_type) \
do_nothing_ ## name(var_type *ptr) \
{ \
/* Will always be true, but compiler doesn't know. */ \
if ((unsigned long)ptr > 0x2) \
return DO_NOTHING_RETURN_ ## which(ptr); \
else \
return DO_NOTHING_RETURN_ ## which(ptr + 1); \
} \
static noinline __init int leaf_ ## name(unsigned long sp, \
bool fill, \
var_type *arg) \
{ \
char buf[VAR_BUFFER]; \
var_type var INIT_ ## which ## _ ## init_level; \
\
target_start = &var; \
target_size = sizeof(var); \
/* \
* Keep this buffer around to make sure we've got a \
* stack frame of SOME kind... \
*/ \
memset(buf, (char)(sp && 0xff), sizeof(buf)); \
/* Fill variable with 0xFF. */ \
if (fill) { \
fill_start = &var; \
fill_size = sizeof(var); \
memset(fill_start, \
(char)((sp && 0xff) | forced_mask), \
fill_size); \
} \
\
/* Silence "never initialized" warnings. */ \
DO_NOTHING_CALL_ ## which(var, name); \
\
/* Exfiltrate "var". */ \
memcpy(check_buf, target_start, target_size); \
\
return (int)buf[0] | (int)buf[sizeof(buf) - 1]; \
} \
DEFINE_TEST_DRIVER(name, var_type, which)
/* Structure with no padding. */
struct test_packed {
unsigned long one;
unsigned long two;
unsigned long three;
unsigned long four;
};
/* Simple structure with padding likely to be covered by compiler. */
struct test_small_hole {
size_t one;
char two;
/* 3 byte padding hole here. */
int three;
unsigned long four;
};
/* Try to trigger unhandled padding in a structure. */
struct test_aligned {
u32 internal1;
u64 internal2;
} __aligned(64);
struct test_big_hole {
u8 one;
u8 two;
u8 three;
/* 61 byte padding hole here. */
struct test_aligned four;
} __aligned(64);
struct test_trailing_hole {
char *one;
char *two;
char *three;
char four;
/* "sizeof(unsigned long) - 1" byte padding hole here. */
};
/* Test if STRUCTLEAK is clearing structs with __user fields. */
struct test_user {
u8 one;
unsigned long two;
char __user *three;
unsigned long four;
};
#define DEFINE_SCALAR_TEST(name, init) \
DEFINE_TEST(name ## _ ## init, name, SCALAR, init)
#define DEFINE_SCALAR_TESTS(init) \
DEFINE_SCALAR_TEST(u8, init); \
DEFINE_SCALAR_TEST(u16, init); \
DEFINE_SCALAR_TEST(u32, init); \
DEFINE_SCALAR_TEST(u64, init); \
DEFINE_TEST(char_array_ ## init, unsigned char, STRING, init)
#define DEFINE_STRUCT_TEST(name, init) \
DEFINE_TEST(name ## _ ## init, \
struct test_ ## name, STRUCT, init)
#define DEFINE_STRUCT_TESTS(init) \
DEFINE_STRUCT_TEST(small_hole, init); \
DEFINE_STRUCT_TEST(big_hole, init); \
DEFINE_STRUCT_TEST(trailing_hole, init); \
DEFINE_STRUCT_TEST(packed, init)
/* These should be fully initialized all the time! */
DEFINE_SCALAR_TESTS(zero);
DEFINE_STRUCT_TESTS(zero);
/* Static initialization: padding may be left uninitialized. */
DEFINE_STRUCT_TESTS(static_partial);
DEFINE_STRUCT_TESTS(static_all);
/* Dynamic initialization: padding may be left uninitialized. */
DEFINE_STRUCT_TESTS(dynamic_partial);
DEFINE_STRUCT_TESTS(dynamic_all);
/* Runtime initialization: padding may be left uninitialized. */
DEFINE_STRUCT_TESTS(runtime_partial);
DEFINE_STRUCT_TESTS(runtime_all);
/* No initialization without compiler instrumentation. */
DEFINE_SCALAR_TESTS(none);
DEFINE_STRUCT_TESTS(none);
DEFINE_TEST(user, struct test_user, STRUCT, none);
/*
* Check two uses through a variable declaration outside either path,
* which was noticed as a special case in porting earlier stack init
* compiler logic.
*/
static int noinline __leaf_switch_none(int path, bool fill)
{
switch (path) {
uint64_t var;
case 1:
target_start = &var;
target_size = sizeof(var);
if (fill) {
fill_start = &var;
fill_size = sizeof(var);
memset(fill_start, forced_mask | 0x55, fill_size);
}
memcpy(check_buf, target_start, target_size);
break;
case 2:
target_start = &var;
target_size = sizeof(var);
if (fill) {
fill_start = &var;
fill_size = sizeof(var);
memset(fill_start, forced_mask | 0xaa, fill_size);
}
memcpy(check_buf, target_start, target_size);
break;
default:
var = 5;
return var & forced_mask;
}
return 0;
}
static noinline __init int leaf_switch_1_none(unsigned long sp, bool fill,
uint64_t *arg)
{
return __leaf_switch_none(1, fill);
}
static noinline __init int leaf_switch_2_none(unsigned long sp, bool fill,
uint64_t *arg)
{
return __leaf_switch_none(2, fill);
}
DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR);
DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR);
static int __init test_stackinit_init(void)
{
unsigned int failures = 0;
#define test_scalars(init) do { \
failures += test_u8_ ## init (); \
failures += test_u16_ ## init (); \
failures += test_u32_ ## init (); \
failures += test_u64_ ## init (); \
failures += test_char_array_ ## init (); \
} while (0)
#define test_structs(init) do { \
failures += test_small_hole_ ## init (); \
failures += test_big_hole_ ## init (); \
failures += test_trailing_hole_ ## init (); \
failures += test_packed_ ## init (); \
} while (0)
/* These are explicitly initialized and should always pass. */
test_scalars(zero);
test_structs(zero);
/* Padding here appears to be accidentally always initialized? */
test_structs(dynamic_partial);
/* Padding initialization depends on compiler behaviors. */
test_structs(static_partial);
test_structs(static_all);
test_structs(dynamic_all);
test_structs(runtime_partial);
test_structs(runtime_all);
/* STRUCTLEAK_BYREF_ALL should cover everything from here down. */
test_scalars(none);
failures += test_switch_1_none();
failures += test_switch_2_none();
/* STRUCTLEAK_BYREF should cover from here down. */
test_structs(none);
/* STRUCTLEAK will only cover this. */
failures += test_user();
if (failures == 0)
pr_info("all tests passed!\n");
else
pr_err("failures: %u\n", failures);
return failures ? -EINVAL : 0;
}
module_init(test_stackinit_init);
static void __exit test_stackinit_exit(void)
{ }
module_exit(test_stackinit_exit);
MODULE_LICENSE("GPL");