From 3bf301e1ab85e18ed0e337ce124dc71d6d7b5fd7 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Tue, 4 Apr 2023 15:43:35 -0700 Subject: [PATCH] string: Add Kunit tests for strcat() family Add tests to make sure the strcat() family of functions behave correctly. Signed-off-by: Kees Cook --- MAINTAINERS | 1 + lib/Kconfig.debug | 5 +++ lib/Makefile | 1 + lib/strcat_kunit.c | 104 +++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 111 insertions(+) create mode 100644 lib/strcat_kunit.c diff --git a/MAINTAINERS b/MAINTAINERS index e0ad886d3163..b2692138c827 100644 --- 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 1a630a03dfcc..c2a7608ff585 100644 --- 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 876fcdeae34e..38c89b52d3ef 100644 --- 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 index 000000000000..e21be95514af --- /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 +#include + +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");