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linux/lib/memcpy_kunit.c
Kees Cook 6dbefad408 string.h: Introduce memset_startat() for wiping trailing members and padding 
A common idiom in kernel code is to wipe the contents of a structure
starting from a given member. These open-coded cases are usually difficult
to read and very sensitive to struct layout changes. Like memset_after(),
introduce a new helper, memset_startat() that takes the target struct
instance, the byte to write, and the member name where zeroing should
start.

Note that this doesn't zero padding preceding the target member. For
those cases, memset_after() should be used on the preceding member.

Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Francis Laniel <laniel_francis@privacyrequired.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Daniel Axtens <dja@axtens.net>
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
2021-10-18 12:28:52 -07:00

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// SPDX-License-Identifier: GPL-2.0
/*
* Test cases for memcpy(), memmove(), and memset().
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <kunit/test.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/overflow.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/vmalloc.h>
struct some_bytes {
union {
u8 data[32];
struct {
u32 one;
u16 two;
u8 three;
/* 1 byte hole */
u32 four[4];
};
};
};
#define check(instance, v) do { \
int i; \
BUILD_BUG_ON(sizeof(instance.data) != 32); \
for (i = 0; i < sizeof(instance.data); i++) { \
KUNIT_ASSERT_EQ_MSG(test, instance.data[i], v, \
"line %d: '%s' not initialized to 0x%02x @ %d (saw 0x%02x)\n", \
__LINE__, #instance, v, i, instance.data[i]); \
} \
} while (0)
#define compare(name, one, two) do { \
int i; \
BUILD_BUG_ON(sizeof(one) != sizeof(two)); \
for (i = 0; i < sizeof(one); i++) { \
KUNIT_EXPECT_EQ_MSG(test, one.data[i], two.data[i], \
"line %d: %s.data[%d] (0x%02x) != %s.data[%d] (0x%02x)\n", \
__LINE__, #one, i, one.data[i], #two, i, two.data[i]); \
} \
kunit_info(test, "ok: " TEST_OP "() " name "\n"); \
} while (0)
static void memcpy_test(struct kunit *test)
{
#define TEST_OP "memcpy"
struct some_bytes control = {
.data = { 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
},
};
struct some_bytes zero = { };
struct some_bytes middle = {
.data = { 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
},
};
struct some_bytes three = {
.data = { 0x00, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x00, 0x00, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
},
};
struct some_bytes dest = { };
int count;
u8 *ptr;
/* Verify static initializers. */
check(control, 0x20);
check(zero, 0);
compare("static initializers", dest, zero);
/* Verify assignment. */
dest = control;
compare("direct assignment", dest, control);
/* Verify complete overwrite. */
memcpy(dest.data, zero.data, sizeof(dest.data));
compare("complete overwrite", dest, zero);
/* Verify middle overwrite. */
dest = control;
memcpy(dest.data + 12, zero.data, 7);
compare("middle overwrite", dest, middle);
/* Verify argument side-effects aren't repeated. */
dest = control;
ptr = dest.data;
count = 1;
memcpy(ptr++, zero.data, count++);
ptr += 8;
memcpy(ptr++, zero.data, count++);
compare("argument side-effects", dest, three);
#undef TEST_OP
}
static void memmove_test(struct kunit *test)
{
#define TEST_OP "memmove"
struct some_bytes control = {
.data = { 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
},
};
struct some_bytes zero = { };
struct some_bytes middle = {
.data = { 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
},
};
struct some_bytes five = {
.data = { 0x00, 0x00, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x00, 0x00, 0x00, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
},
};
struct some_bytes overlap = {
.data = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
},
};
struct some_bytes overlap_expected = {
.data = { 0x00, 0x01, 0x00, 0x01, 0x02, 0x03, 0x04, 0x07,
0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
},
};
struct some_bytes dest = { };
int count;
u8 *ptr;
/* Verify static initializers. */
check(control, 0x99);
check(zero, 0);
compare("static initializers", zero, dest);
/* Verify assignment. */
dest = control;
compare("direct assignment", dest, control);
/* Verify complete overwrite. */
memmove(dest.data, zero.data, sizeof(dest.data));
compare("complete overwrite", dest, zero);
/* Verify middle overwrite. */
dest = control;
memmove(dest.data + 12, zero.data, 7);
compare("middle overwrite", dest, middle);
/* Verify argument side-effects aren't repeated. */
dest = control;
ptr = dest.data;
count = 2;
memmove(ptr++, zero.data, count++);
ptr += 9;
memmove(ptr++, zero.data, count++);
compare("argument side-effects", dest, five);
/* Verify overlapping overwrite is correct. */
ptr = &overlap.data[2];
memmove(ptr, overlap.data, 5);
compare("overlapping write", overlap, overlap_expected);
#undef TEST_OP
}
static void memset_test(struct kunit *test)
{
#define TEST_OP "memset"
struct some_bytes control = {
.data = { 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
},
};
struct some_bytes complete = {
.data = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
},
};
struct some_bytes middle = {
.data = { 0x30, 0x30, 0x30, 0x30, 0x31, 0x31, 0x31, 0x31,
0x31, 0x31, 0x31, 0x31, 0x31, 0x31, 0x31, 0x31,
0x31, 0x31, 0x31, 0x31, 0x30, 0x30, 0x30, 0x30,
0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
},
};
struct some_bytes three = {
.data = { 0x60, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
0x30, 0x61, 0x61, 0x30, 0x30, 0x30, 0x30, 0x30,
0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
},
};
struct some_bytes after = {
.data = { 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x72,
0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72,
0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72,
0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72,
},
};
struct some_bytes startat = {
.data = { 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
0x79, 0x79, 0x79, 0x79, 0x79, 0x79, 0x79, 0x79,
0x79, 0x79, 0x79, 0x79, 0x79, 0x79, 0x79, 0x79,
0x79, 0x79, 0x79, 0x79, 0x79, 0x79, 0x79, 0x79,
},
};
struct some_bytes dest = { };
int count, value;
u8 *ptr;
/* Verify static initializers. */
check(control, 0x30);
check(dest, 0);
/* Verify assignment. */
dest = control;
compare("direct assignment", dest, control);
/* Verify complete overwrite. */
memset(dest.data, 0xff, sizeof(dest.data));
compare("complete overwrite", dest, complete);
/* Verify middle overwrite. */
dest = control;
memset(dest.data + 4, 0x31, 16);
compare("middle overwrite", dest, middle);
/* Verify argument side-effects aren't repeated. */
dest = control;
ptr = dest.data;
value = 0x60;
count = 1;
memset(ptr++, value++, count++);
ptr += 8;
memset(ptr++, value++, count++);
compare("argument side-effects", dest, three);
/* Verify memset_after() */
dest = control;
memset_after(&dest, 0x72, three);
compare("memset_after()", dest, after);
/* Verify memset_startat() */
dest = control;
memset_startat(&dest, 0x79, four);
compare("memset_startat()", dest, startat);
#undef TEST_OP
}
static struct kunit_case memcpy_test_cases[] = {
KUNIT_CASE(memset_test),
KUNIT_CASE(memcpy_test),
KUNIT_CASE(memmove_test),
{}
};
static struct kunit_suite memcpy_test_suite = {
.name = "memcpy",
.test_cases = memcpy_test_cases,
};
kunit_test_suite(memcpy_test_suite);
MODULE_LICENSE("GPL");
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