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>

diff --git a/MAINTAINERS b/MAINTAINERS
index e0ad886..b269213 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -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:     lib/fortify_kunit.c
 F:     lib/memcpy_kunit.c
+F:     lib/strcat_kunit.c
 F:     lib/strscpy_kunit.c
 F:     lib/test_fortify/*
 F:     scripts/test_fortify.sh

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 1a630a0..c2a7608 100644 (file)
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2662,6 +2662,11 @@ config HW_BREAKPOINT_KUNIT_TEST
 
          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
        tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS
        depends on KUNIT

diff --git a/lib/Makefile b/lib/Makefile
index 876fcde..38c89b5 100644 (file)
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -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 += $(DISABLE_STRUCTLEAK_PLUGIN)
 obj-$(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_SIPHASH_KUNIT_TEST) += siphash_kunit.o
 

diff --git a/lib/strcat_kunit.c b/lib/strcat_kunit.c
new file mode 100644 (file)
index 0000000..e21be95
--- /dev/null
+++ b/lib/strcat_kunit.c
@@ -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");