string: Add Kunit tests for strcat() family

Add tests to make sure the strcat() family of functions behave
correctly.

Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook 2023-04-04 15:43:35 -07:00
parent a9dc8d0442
commit 3bf301e1ab
4 changed files with 111 additions and 0 deletions

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@ -8061,6 +8061,7 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/har
F: include/linux/fortify-string.h F: include/linux/fortify-string.h
F: lib/fortify_kunit.c F: lib/fortify_kunit.c
F: lib/memcpy_kunit.c F: lib/memcpy_kunit.c
F: lib/strcat_kunit.c
F: lib/strscpy_kunit.c F: lib/strscpy_kunit.c
F: lib/test_fortify/* F: lib/test_fortify/*
F: scripts/test_fortify.sh F: scripts/test_fortify.sh

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@ -2662,6 +2662,11 @@ config HW_BREAKPOINT_KUNIT_TEST
If unsure, say N. If unsure, say N.
config STRCAT_KUNIT_TEST
tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
config STRSCPY_KUNIT_TEST config STRSCPY_KUNIT_TEST
tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS
depends on KUNIT depends on KUNIT

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@ -392,6 +392,7 @@ 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, unsequenced)
CFLAGS_fortify_kunit.o += $(DISABLE_STRUCTLEAK_PLUGIN) CFLAGS_fortify_kunit.o += $(DISABLE_STRUCTLEAK_PLUGIN)
obj-$(CONFIG_FORTIFY_KUNIT_TEST) += fortify_kunit.o obj-$(CONFIG_FORTIFY_KUNIT_TEST) += fortify_kunit.o
obj-$(CONFIG_STRCAT_KUNIT_TEST) += strcat_kunit.o
obj-$(CONFIG_STRSCPY_KUNIT_TEST) += strscpy_kunit.o obj-$(CONFIG_STRSCPY_KUNIT_TEST) += strscpy_kunit.o
obj-$(CONFIG_SIPHASH_KUNIT_TEST) += siphash_kunit.o obj-$(CONFIG_SIPHASH_KUNIT_TEST) += siphash_kunit.o

104
lib/strcat_kunit.c Normal file
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@ -0,0 +1,104 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Kernel module for testing 'strcat' family of functions.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <kunit/test.h>
#include <linux/string.h>
static volatile int unconst;
static void strcat_test(struct kunit *test)
{
char dest[8];
/* Destination is terminated. */
memset(dest, 0, sizeof(dest));
KUNIT_EXPECT_EQ(test, strlen(dest), 0);
/* Empty copy does nothing. */
KUNIT_EXPECT_TRUE(test, strcat(dest, "") == dest);
KUNIT_EXPECT_STREQ(test, dest, "");
/* 4 characters copied in, stops at %NUL. */
KUNIT_EXPECT_TRUE(test, strcat(dest, "four\000123") == dest);
KUNIT_EXPECT_STREQ(test, dest, "four");
KUNIT_EXPECT_EQ(test, dest[5], '\0');
/* 2 more characters copied in okay. */
KUNIT_EXPECT_TRUE(test, strcat(dest, "AB") == dest);
KUNIT_EXPECT_STREQ(test, dest, "fourAB");
}
static void strncat_test(struct kunit *test)
{
char dest[8];
/* Destination is terminated. */
memset(dest, 0, sizeof(dest));
KUNIT_EXPECT_EQ(test, strlen(dest), 0);
/* Empty copy of size 0 does nothing. */
KUNIT_EXPECT_TRUE(test, strncat(dest, "", 0 + unconst) == dest);
KUNIT_EXPECT_STREQ(test, dest, "");
/* Empty copy of size 1 does nothing too. */
KUNIT_EXPECT_TRUE(test, strncat(dest, "", 1 + unconst) == dest);
KUNIT_EXPECT_STREQ(test, dest, "");
/* Copy of max 0 characters should do nothing. */
KUNIT_EXPECT_TRUE(test, strncat(dest, "asdf", 0 + unconst) == dest);
KUNIT_EXPECT_STREQ(test, dest, "");
/* 4 characters copied in, even if max is 8. */
KUNIT_EXPECT_TRUE(test, strncat(dest, "four\000123", 8 + unconst) == dest);
KUNIT_EXPECT_STREQ(test, dest, "four");
KUNIT_EXPECT_EQ(test, dest[5], '\0');
KUNIT_EXPECT_EQ(test, dest[6], '\0');
/* 2 characters copied in okay, 2 ignored. */
KUNIT_EXPECT_TRUE(test, strncat(dest, "ABCD", 2 + unconst) == dest);
KUNIT_EXPECT_STREQ(test, dest, "fourAB");
}
static void strlcat_test(struct kunit *test)
{
char dest[8] = "";
int len = sizeof(dest) + unconst;
/* Destination is terminated. */
KUNIT_EXPECT_EQ(test, strlen(dest), 0);
/* Empty copy is size 0. */
KUNIT_EXPECT_EQ(test, strlcat(dest, "", len), 0);
KUNIT_EXPECT_STREQ(test, dest, "");
/* Size 1 should keep buffer terminated, report size of source only. */
KUNIT_EXPECT_EQ(test, strlcat(dest, "four", 1 + unconst), 4);
KUNIT_EXPECT_STREQ(test, dest, "");
/* 4 characters copied in. */
KUNIT_EXPECT_EQ(test, strlcat(dest, "four", len), 4);
KUNIT_EXPECT_STREQ(test, dest, "four");
/* 2 characters copied in okay, gets to 6 total. */
KUNIT_EXPECT_EQ(test, strlcat(dest, "AB", len), 6);
KUNIT_EXPECT_STREQ(test, dest, "fourAB");
/* 2 characters ignored if max size (7) reached. */
KUNIT_EXPECT_EQ(test, strlcat(dest, "CD", 7 + unconst), 8);
KUNIT_EXPECT_STREQ(test, dest, "fourAB");
/* 1 of 2 characters skipped, now at true max size. */
KUNIT_EXPECT_EQ(test, strlcat(dest, "EFG", len), 9);
KUNIT_EXPECT_STREQ(test, dest, "fourABE");
/* Everything else ignored, now at full size. */
KUNIT_EXPECT_EQ(test, strlcat(dest, "1234", len), 11);
KUNIT_EXPECT_STREQ(test, dest, "fourABE");
}
static struct kunit_case strcat_test_cases[] = {
KUNIT_CASE(strcat_test),
KUNIT_CASE(strncat_test),
KUNIT_CASE(strlcat_test),
{}
};
static struct kunit_suite strcat_test_suite = {
.name = "strcat",
.test_cases = strcat_test_cases,
};
kunit_test_suite(strcat_test_suite);
MODULE_LICENSE("GPL");