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Date:   Wed,  2 Dec 2020 16:44:37 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Kees Cook <keescook@...omium.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Ard Biesheuvel <ardb@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nathan Chancellor <natechancellor@...il.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Marco Elver <elver@...gle.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        George Popescu <georgepope@...roid.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Peter Oberparleiter <oberpar@...ux.ibm.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        clang-built-linux@...glegroups.com, linux-kbuild@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 7/7] ubsan: Expand tests and reporting

Expand the UBSAN tests to include some additional UB cases. Notably the
out-of-bounds enum loading appears not to work. Also include per-test
reporting, including the relevant CONFIG_UBSAN... Kconfigs.

Signed-off-by: Kees Cook <keescook@...omium.org>
---
 lib/test_ubsan.c | 74 ++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 66 insertions(+), 8 deletions(-)

diff --git a/lib/test_ubsan.c b/lib/test_ubsan.c
index 9ea10adf7a66..5e5d9355ef49 100644
--- a/lib/test_ubsan.c
+++ b/lib/test_ubsan.c
@@ -5,32 +5,54 @@
 
 typedef void(*test_ubsan_fp)(void);
 
+#define UBSAN_TEST(config, ...)	do {					\
+		pr_info("%s " __VA_ARGS__ "%s(%s=%s)\n", __func__,	\
+			sizeof(" " __VA_ARGS__) > 2 ? " " : "",		\
+			#config, IS_ENABLED(config) ? "y" : "n");	\
+	} while (0)
+
 static void test_ubsan_add_overflow(void)
 {
 	volatile int val = INT_MAX;
+	volatile unsigned int uval = UINT_MAX;
 
+	UBSAN_TEST(CONFIG_UBSAN_SIGNED_OVERFLOW);
 	val += 2;
+
+	UBSAN_TEST(CONFIG_UBSAN_UNSIGNED_OVERFLOW);
+	uval += 2;
 }
 
 static void test_ubsan_sub_overflow(void)
 {
 	volatile int val = INT_MIN;
+	volatile unsigned int uval = 0;
 	volatile int val2 = 2;
 
+	UBSAN_TEST(CONFIG_UBSAN_SIGNED_OVERFLOW);
 	val -= val2;
+
+	UBSAN_TEST(CONFIG_UBSAN_UNSIGNED_OVERFLOW);
+	uval -= val2;
 }
 
 static void test_ubsan_mul_overflow(void)
 {
 	volatile int val = INT_MAX / 2;
+	volatile unsigned int uval = UINT_MAX / 2;
 
+	UBSAN_TEST(CONFIG_UBSAN_SIGNED_OVERFLOW);
 	val *= 3;
+
+	UBSAN_TEST(CONFIG_UBSAN_UNSIGNED_OVERFLOW);
+	uval *= 3;
 }
 
 static void test_ubsan_negate_overflow(void)
 {
 	volatile int val = INT_MIN;
 
+	UBSAN_TEST(CONFIG_UBSAN_SIGNED_OVERFLOW);
 	val = -val;
 }
 
@@ -39,37 +61,67 @@ static void test_ubsan_divrem_overflow(void)
 	volatile int val = 16;
 	volatile int val2 = 0;
 
+	UBSAN_TEST(CONFIG_UBSAN_DIV_ZERO);
 	val /= val2;
 }
 
 static void test_ubsan_shift_out_of_bounds(void)
 {
-	volatile int val = -1;
-	int val2 = 10;
+	volatile int neg = -1, wrap = 4;
+	int val1 = 10;
+	int val2 = INT_MAX;
+
+	UBSAN_TEST(CONFIG_UBSAN_SHIFT, "negative exponent");
+	val1 <<= neg;
 
-	val2 <<= val;
+	UBSAN_TEST(CONFIG_UBSAN_SHIFT, "left overflow");
+	val2 <<= wrap;
 }
 
 static void test_ubsan_out_of_bounds(void)
 {
-	volatile int i = 4, j = 5;
+	volatile int i = 4, j = 5, k = -1;
+	volatile char above[4] = { }; /* Protect surrounding memory. */
 	volatile int arr[4];
+	volatile char below[4] = { }; /* Protect surrounding memory. */
 
+	above[0] = below[0];
+
+	UBSAN_TEST(CONFIG_UBSAN_BOUNDS, "above");
 	arr[j] = i;
+
+	UBSAN_TEST(CONFIG_UBSAN_BOUNDS, "below");
+	arr[k] = i;
 }
 
+enum ubsan_test_enum {
+	UBSAN_TEST_ZERO = 0,
+	UBSAN_TEST_ONE,
+	UBSAN_TEST_MAX,
+};
+
 static void test_ubsan_load_invalid_value(void)
 {
 	volatile char *dst, *src;
 	bool val, val2, *ptr;
-	char c = 4;
+	enum ubsan_test_enum eval, eval2, *eptr;
+	unsigned char c = 0xff;
 
+	UBSAN_TEST(CONFIG_UBSAN_BOOL, "bool");
 	dst = (char *)&val;
 	src = &c;
 	*dst = *src;
 
 	ptr = &val2;
 	val2 = val;
+
+	UBSAN_TEST(CONFIG_UBSAN_ENUM, "enum");
+	dst = (char *)&eval;
+	src = &c;
+	*dst = *src;
+
+	eptr = &eval2;
+	eval2 = eval;
 }
 
 static void test_ubsan_null_ptr_deref(void)
@@ -77,6 +129,7 @@ static void test_ubsan_null_ptr_deref(void)
 	volatile int *ptr = NULL;
 	int val;
 
+	UBSAN_TEST(CONFIG_UBSAN_OBJECT_SIZE);
 	val = *ptr;
 }
 
@@ -85,6 +138,7 @@ static void test_ubsan_misaligned_access(void)
 	volatile char arr[5] __aligned(4) = {1, 2, 3, 4, 5};
 	volatile int *ptr, val = 6;
 
+	UBSAN_TEST(CONFIG_UBSAN_ALIGNMENT);
 	ptr = (int *)(arr + 1);
 	*ptr = val;
 }
@@ -95,6 +149,7 @@ static void test_ubsan_object_size_mismatch(void)
 	volatile int val __aligned(8) = 4;
 	volatile long long *ptr, val2;
 
+	UBSAN_TEST(CONFIG_UBSAN_OBJECT_SIZE);
 	ptr = (long long *)&val;
 	val2 = *ptr;
 }
@@ -104,15 +159,19 @@ static const test_ubsan_fp test_ubsan_array[] = {
 	test_ubsan_sub_overflow,
 	test_ubsan_mul_overflow,
 	test_ubsan_negate_overflow,
-	test_ubsan_divrem_overflow,
 	test_ubsan_shift_out_of_bounds,
 	test_ubsan_out_of_bounds,
 	test_ubsan_load_invalid_value,
-	//test_ubsan_null_ptr_deref, /* exclude it because there is a crash */
 	test_ubsan_misaligned_access,
 	test_ubsan_object_size_mismatch,
 };
 
+/* Excluded because they Oops the module. */
+static const test_ubsan_fp skip_ubsan_array[] = {
+	test_ubsan_divrem_overflow,
+	test_ubsan_null_ptr_deref,
+};
+
 static int __init test_ubsan_init(void)
 {
 	unsigned int i;
@@ -120,7 +179,6 @@ static int __init test_ubsan_init(void)
 	for (i = 0; i < ARRAY_SIZE(test_ubsan_array); i++)
 		test_ubsan_array[i]();
 
-	(void)test_ubsan_null_ptr_deref; /* to avoid unsed-function warning */
 	return 0;
 }
 module_init(test_ubsan_init);
-- 
2.25.1

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