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Commit fa4a3f86 authored by Kees Cook's avatar Kees Cook
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fortify: Add KUnit tests for runtime overflows 

With fortify overflows able to be redirected, we can use KUnit to
exercise the overflow conditions. Add tests for every API covered by
CONFIG_FORTIFY_SOURCE, except for memset() and memcpy(), which are
special-cased for now.

Disable warnings in the Makefile since we're explicitly testing
known-bad string handling code patterns.

Note that this makes the LKDTM FORTIFY_STR* tests obsolete, but those
can be removed separately.
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
parent 4ce615e7
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Showing with 607 additions and 2 deletions
lib/Makefile
View file @ fa4a3f86
......@@ -402,6 +402,8 @@ obj-$(CONFIG_OVERFLOW_KUNIT_TEST) += overflow_kunit.o
CFLAGS_stackinit_kunit.o += $(call cc-disable-warning, switch-unreachable)
obj-$(CONFIG_STACKINIT_KUNIT_TEST) += stackinit_kunit.o
CFLAGS_fortify_kunit.o += $(call cc-disable-warning, unsequenced)
CFLAGS_fortify_kunit.o += $(call cc-disable-warning, stringop-overread)
CFLAGS_fortify_kunit.o += $(call cc-disable-warning, stringop-truncation)
CFLAGS_fortify_kunit.o += $(DISABLE_STRUCTLEAK_PLUGIN)
obj-$(CONFIG_FORTIFY_KUNIT_TEST) += fortify_kunit.o
obj-$(CONFIG_STRCAT_KUNIT_TEST) += strcat_kunit.o
......
lib/fortify_kunit.c
View file @ fa4a3f86
// SPDX-License-Identifier: GPL-2.0
/*
* Runtime test cases for CONFIG_FORTIFY_SOURCE that aren't expected to
* Oops the kernel on success. (For those, see drivers/misc/lkdtm/fortify.c)
* Runtime test cases for CONFIG_FORTIFY_SOURCE. For testing memcpy(),
* see FORTIFY_MEM_* tests in LKDTM (drivers/misc/lkdtm/fortify.c).
*
* For corner cases with UBSAN, try testing with:
*
......@@ -346,6 +346,594 @@ DEFINE_ALLOC_SIZE_TEST_PAIR(kvmalloc)
} while (0)
DEFINE_ALLOC_SIZE_TEST_PAIR(devm_kmalloc)
/*
* We can't have an array at the end of a structure or else
* builds without -fstrict-flex-arrays=3 will report them as
* being an unknown length. Additionally, add bytes before
* and after the string to catch over/underflows if tests
* fail.
*/
struct fortify_padding {
unsigned long bytes_before;
char buf[32];
unsigned long bytes_after;
};
/* Force compiler into not being able to resolve size at compile-time. */
static volatile int unconst;
static void strlen_test(struct kunit *test)
{
struct fortify_padding pad = { };
int i, end = sizeof(pad.buf) - 1;
/* Fill 31 bytes with valid characters. */
for (i = 0; i < sizeof(pad.buf) - 1; i++)
pad.buf[i] = i + '0';
/* Trailing bytes are still %NUL. */
KUNIT_EXPECT_EQ(test, pad.buf[end], '\0');
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
/* String is terminated, so strlen() is valid. */
KUNIT_EXPECT_EQ(test, strlen(pad.buf), end);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
/* Make string unterminated, and recount. */
pad.buf[end] = 'A';
end = sizeof(pad.buf);
KUNIT_EXPECT_EQ(test, strlen(pad.buf), end);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
}
static void strnlen_test(struct kunit *test)
{
struct fortify_padding pad = { };
int i, end = sizeof(pad.buf) - 1;
/* Fill 31 bytes with valid characters. */
for (i = 0; i < sizeof(pad.buf) - 1; i++)
pad.buf[i] = i + '0';
/* Trailing bytes are still %NUL. */
KUNIT_EXPECT_EQ(test, pad.buf[end], '\0');
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
/* String is terminated, so strnlen() is valid. */
KUNIT_EXPECT_EQ(test, strnlen(pad.buf, sizeof(pad.buf)), end);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
/* A truncated strnlen() will be safe, too. */
KUNIT_EXPECT_EQ(test, strnlen(pad.buf, sizeof(pad.buf) / 2),
sizeof(pad.buf) / 2);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
/* Make string unterminated, and recount. */
pad.buf[end] = 'A';
end = sizeof(pad.buf);
/* Reading beyond with strncpy() will fail. */
KUNIT_EXPECT_EQ(test, strnlen(pad.buf, end + 1), end);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
KUNIT_EXPECT_EQ(test, strnlen(pad.buf, end + 2), end);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
/* Early-truncated is safe still, though. */
KUNIT_EXPECT_EQ(test, strnlen(pad.buf, end), end);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
end = sizeof(pad.buf) / 2;
KUNIT_EXPECT_EQ(test, strnlen(pad.buf, end), end);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
}
static void strcpy_test(struct kunit *test)
{
struct fortify_padding pad = { };
char src[sizeof(pad.buf) + 1] = { };
int i;
/* Fill 31 bytes with valid characters. */
for (i = 0; i < sizeof(src) - 2; i++)
src[i] = i + '0';
/* Destination is %NUL-filled to start with. */
KUNIT_EXPECT_EQ(test, pad.bytes_before, 0);
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0');
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
/* Legitimate strcpy() 1 less than of max size. */
KUNIT_ASSERT_TRUE(test, strcpy(pad.buf, src)
== pad.buf);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
/* Only last byte should be %NUL */
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
src[sizeof(src) - 2] = 'A';
/* But now we trip the overflow checking. */
KUNIT_ASSERT_TRUE(test, strcpy(pad.buf, src)
== pad.buf);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);
/* Trailing %NUL -- thanks to FORTIFY. */
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
/* And we will not have gone beyond. */
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
src[sizeof(src) - 1] = 'A';
/* And for sure now, two bytes past. */
KUNIT_ASSERT_TRUE(test, strcpy(pad.buf, src)
== pad.buf);
/*
* Which trips both the strlen() on the unterminated src,
* and the resulting copy attempt.
*/
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
/* Trailing %NUL -- thanks to FORTIFY. */
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
/* And we will not have gone beyond. */
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
}
static void strncpy_test(struct kunit *test)
{
struct fortify_padding pad = { };
char src[] = "Copy me fully into a small buffer and I will overflow!";
/* Destination is %NUL-filled to start with. */
KUNIT_EXPECT_EQ(test, pad.bytes_before, 0);
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0');
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
/* Legitimate strncpy() 1 less than of max size. */
KUNIT_ASSERT_TRUE(test, strncpy(pad.buf, src,
sizeof(pad.buf) + unconst - 1)
== pad.buf);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
/* Only last byte should be %NUL */
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
/* Legitimate (though unterminated) max-size strncpy. */
KUNIT_ASSERT_TRUE(test, strncpy(pad.buf, src,
sizeof(pad.buf) + unconst)
== pad.buf);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
/* No trailing %NUL -- thanks strncpy API. */
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
/* But we will not have gone beyond. */
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
/* Now verify that FORTIFY is working... */
KUNIT_ASSERT_TRUE(test, strncpy(pad.buf, src,
sizeof(pad.buf) + unconst + 1)
== pad.buf);
/* Should catch the overflow. */
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
/* And we will not have gone beyond. */
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
/* And further... */
KUNIT_ASSERT_TRUE(test, strncpy(pad.buf, src,
sizeof(pad.buf) + unconst + 2)
== pad.buf);
/* Should catch the overflow. */
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
/* And we will not have gone beyond. */
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
}
static void strscpy_test(struct kunit *test)
{
struct fortify_padding pad = { };
char src[] = "Copy me fully into a small buffer and I will overflow!";
/* Destination is %NUL-filled to start with. */
KUNIT_EXPECT_EQ(test, pad.bytes_before, 0);
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0');
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
/* Legitimate strscpy() 1 less than of max size. */
KUNIT_ASSERT_EQ(test, strscpy(pad.buf, src,
sizeof(pad.buf) + unconst - 1),
-E2BIG);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
/* Keeping space for %NUL, last two bytes should be %NUL */
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
/* Legitimate max-size strscpy. */
KUNIT_ASSERT_EQ(test, strscpy(pad.buf, src,
sizeof(pad.buf) + unconst),
-E2BIG);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
/* A trailing %NUL will exist. */
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
/* Now verify that FORTIFY is working... */
KUNIT_ASSERT_EQ(test, strscpy(pad.buf, src,
sizeof(pad.buf) + unconst + 1),
-E2BIG);
/* Should catch the overflow. */
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
/* And we will not have gone beyond. */
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
/* And much further... */
KUNIT_ASSERT_EQ(test, strscpy(pad.buf, src,
sizeof(src) * 2 + unconst),
-E2BIG);
/* Should catch the overflow. */
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
/* And we will not have gone beyond. */
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
}
static void strcat_test(struct kunit *test)
{
struct fortify_padding pad = { };
char src[sizeof(pad.buf) / 2] = { };
char one[] = "A";
char two[] = "BC";
int i;
/* Fill 15 bytes with valid characters. */
for (i = 0; i < sizeof(src) - 1; i++)
src[i] = i + 'A';
/* Destination is %NUL-filled to start with. */
KUNIT_EXPECT_EQ(test, pad.bytes_before, 0);
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0');
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
/* Legitimate strcat() using less than half max size. */
KUNIT_ASSERT_TRUE(test, strcat(pad.buf, src) == pad.buf);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
/* Legitimate strcat() now 2 bytes shy of end. */
KUNIT_ASSERT_TRUE(test, strcat(pad.buf, src) == pad.buf);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
/* Last two bytes should be %NUL */
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
/* Add one more character to the end. */
KUNIT_ASSERT_TRUE(test, strcat(pad.buf, one) == pad.buf);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
/* Last byte should be %NUL */
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
/* And this one char will overflow. */
KUNIT_ASSERT_TRUE(test, strcat(pad.buf, one) == pad.buf);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);
/* Last byte should be %NUL thanks to FORTIFY. */
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
/* And adding two will overflow more. */
KUNIT_ASSERT_TRUE(test, strcat(pad.buf, two) == pad.buf);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
/* Last byte should be %NUL thanks to FORTIFY. */
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
}
static void strncat_test(struct kunit *test)
{
struct fortify_padding pad = { };
char src[sizeof(pad.buf)] = { };
int i, partial;
/* Fill 31 bytes with valid characters. */
partial = sizeof(src) / 2 - 1;
for (i = 0; i < partial; i++)
src[i] = i + 'A';
/* Destination is %NUL-filled to start with. */
KUNIT_EXPECT_EQ(test, pad.bytes_before, 0);
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0');
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
/* Legitimate strncat() using less than half max size. */
KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, partial) == pad.buf);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
/* Legitimate strncat() now 2 bytes shy of end. */
KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, partial) == pad.buf);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
/* Last two bytes should be %NUL */
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
/* Add one more character to the end. */
KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, 1) == pad.buf);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
/* Last byte should be %NUL */
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
/* And this one char will overflow. */
KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, 1) == pad.buf);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);
/* Last byte should be %NUL thanks to FORTIFY. */
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
/* And adding two will overflow more. */
KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, 2) == pad.buf);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
/* Last byte should be %NUL thanks to FORTIFY. */
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
/* Force an unterminated destination, and overflow. */
pad.buf[sizeof(pad.buf) - 1] = 'A';
KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, 1) == pad.buf);
/* This will have tripped both strlen() and strcat(). */
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 3);
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
/* But we should not go beyond the end. */
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
}
static void strlcat_test(struct kunit *test)
{
struct fortify_padding pad = { };
char src[sizeof(pad.buf)] = { };
int i, partial;
int len = sizeof(pad.buf) + unconst;
/* Fill 15 bytes with valid characters. */
partial = sizeof(src) / 2 - 1;
for (i = 0; i < partial; i++)
src[i] = i + 'A';
/* Destination is %NUL-filled to start with. */
KUNIT_EXPECT_EQ(test, pad.bytes_before, 0);
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0');
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
/* Legitimate strlcat() using less than half max size. */
KUNIT_ASSERT_EQ(test, strlcat(pad.buf, src, len), partial);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
/* Legitimate strlcat() now 2 bytes shy of end. */
KUNIT_ASSERT_EQ(test, strlcat(pad.buf, src, len), partial * 2);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
/* Last two bytes should be %NUL */
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
/* Add one more character to the end. */
KUNIT_ASSERT_EQ(test, strlcat(pad.buf, "Q", len), partial * 2 + 1);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
/* Last byte should be %NUL */
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
/* And this one char will overflow. */
KUNIT_ASSERT_EQ(test, strlcat(pad.buf, "V", len * 2), len);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);
/* Last byte should be %NUL thanks to FORTIFY. */
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
/* And adding two will overflow more. */
KUNIT_ASSERT_EQ(test, strlcat(pad.buf, "QQ", len * 2), len + 1);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
/* Last byte should be %NUL thanks to FORTIFY. */
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
/* Force an unterminated destination, and overflow. */
pad.buf[sizeof(pad.buf) - 1] = 'A';
KUNIT_ASSERT_EQ(test, strlcat(pad.buf, "TT", len * 2), len + 2);
/* This will have tripped both strlen() and strlcat(). */
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 1], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
/* But we should not go beyond the end. */
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
/* Force an unterminated source, and overflow. */
memset(src, 'B', sizeof(src));
pad.buf[sizeof(pad.buf) - 1] = '\0';
KUNIT_ASSERT_EQ(test, strlcat(pad.buf, src, len * 3), len - 1 + sizeof(src));
/* This will have tripped both strlen() and strlcat(). */
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 3);
KUNIT_EXPECT_EQ(test, fortify_write_overflows, 3);
KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
/* But we should not go beyond the end. */
KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
}
static void memscan_test(struct kunit *test)
{
char haystack[] = "Where oh where is my memory range?";
char *mem = haystack + strlen("Where oh where is ");
char needle = 'm';
size_t len = sizeof(haystack) + unconst;
KUNIT_ASSERT_PTR_EQ(test, memscan(haystack, needle, len),
mem);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
/* Catch too-large range. */
KUNIT_ASSERT_PTR_EQ(test, memscan(haystack, needle, len + 1),
NULL);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
KUNIT_ASSERT_PTR_EQ(test, memscan(haystack, needle, len * 2),
NULL);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
}
static void memchr_test(struct kunit *test)
{
char haystack[] = "Where oh where is my memory range?";
char *mem = haystack + strlen("Where oh where is ");
char needle = 'm';
size_t len = sizeof(haystack) + unconst;
KUNIT_ASSERT_PTR_EQ(test, memchr(haystack, needle, len),
mem);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
/* Catch too-large range. */
KUNIT_ASSERT_PTR_EQ(test, memchr(haystack, needle, len + 1),
NULL);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
KUNIT_ASSERT_PTR_EQ(test, memchr(haystack, needle, len * 2),
NULL);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
}
static void memchr_inv_test(struct kunit *test)
{
char haystack[] = "Where oh where is my memory range?";
char *mem = haystack + 1;
char needle = 'W';
size_t len = sizeof(haystack) + unconst;
/* Normal search is okay. */
KUNIT_ASSERT_PTR_EQ(test, memchr_inv(haystack, needle, len),
mem);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
/* Catch too-large range. */
KUNIT_ASSERT_PTR_EQ(test, memchr_inv(haystack, needle, len + 1),
NULL);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
KUNIT_ASSERT_PTR_EQ(test, memchr_inv(haystack, needle, len * 2),
NULL);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
}
static void memcmp_test(struct kunit *test)
{
char one[] = "My mind is going ...";
char two[] = "My mind is going ... I can feel it.";
size_t one_len = sizeof(one) + unconst - 1;
size_t two_len = sizeof(two) + unconst - 1;
/* We match the first string (ignoring the %NUL). */
KUNIT_ASSERT_EQ(test, memcmp(one, two, one_len), 0);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
/* Still in bounds, but no longer matching. */
KUNIT_ASSERT_EQ(test, memcmp(one, two, one_len + 1), -32);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
/* Catch too-large ranges. */
KUNIT_ASSERT_EQ(test, memcmp(one, two, one_len + 2), INT_MIN);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
KUNIT_ASSERT_EQ(test, memcmp(two, one, two_len + 2), INT_MIN);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
}
static void kmemdup_test(struct kunit *test)
{
char src[] = "I got Doom running on it!";
char *copy;
size_t len = sizeof(src) + unconst;
/* Copy is within bounds. */
copy = kmemdup(src, len, GFP_KERNEL);
KUNIT_EXPECT_NOT_NULL(test, copy);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
kfree(copy);
/* Without %NUL. */
copy = kmemdup(src, len - 1, GFP_KERNEL);
KUNIT_EXPECT_NOT_NULL(test, copy);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
kfree(copy);
/* Tiny bounds. */
copy = kmemdup(src, 1, GFP_KERNEL);
KUNIT_EXPECT_NOT_NULL(test, copy);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
kfree(copy);
/* Out of bounds by 1 byte. */
copy = kmemdup(src, len + 1, GFP_KERNEL);
KUNIT_EXPECT_NULL(test, copy);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
kfree(copy);
/* Way out of bounds. */
copy = kmemdup(src, len * 2, GFP_KERNEL);
KUNIT_EXPECT_NULL(test, copy);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
kfree(copy);
/* Starting offset causing out of bounds. */
copy = kmemdup(src + 1, len, GFP_KERNEL);
KUNIT_EXPECT_NULL(test, copy);
KUNIT_EXPECT_EQ(test, fortify_read_overflows, 3);
kfree(copy);
}
static int fortify_test_init(struct kunit *test)
{
if (!IS_ENABLED(CONFIG_FORTIFY_SOURCE))
......@@ -373,6 +961,21 @@ static struct kunit_case fortify_test_cases[] = {
KUNIT_CASE(alloc_size_kvmalloc_dynamic_test),
KUNIT_CASE(alloc_size_devm_kmalloc_const_test),
KUNIT_CASE(alloc_size_devm_kmalloc_dynamic_test),
KUNIT_CASE(strlen_test),
KUNIT_CASE(strnlen_test),
KUNIT_CASE(strcpy_test),
KUNIT_CASE(strncpy_test),
KUNIT_CASE(strscpy_test),
KUNIT_CASE(strcat_test),
KUNIT_CASE(strncat_test),
KUNIT_CASE(strlcat_test),
/* skip memset: performs bounds checking on whole structs */
/* skip memcpy: still using warn-and-overwrite instead of hard-fail */
KUNIT_CASE(memscan_test),
KUNIT_CASE(memchr_test),
KUNIT_CASE(memchr_inv_test),
KUNIT_CASE(memcmp_test),
KUNIT_CASE(kmemdup_test),
{}
};
......
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