[PATCH -tip v4 3/3] kasan: test: Fix test for new meminstrinsic instrumentation

[Marco Elver]

The tests for memset/memmove have been failing since they haven't been
instrumented in 69d4c0d32186.

Fix the test to recognize when memintrinsics aren't instrumented, and
skip test cases accordingly. We also need to conditionally pass
-fno-builtin to the test, otherwise the instrumentation pass won't
recognize memintrinsics and end up not instrumenting them either.

Fixes: 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*() functions")
Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
---
v4:
* New patch.
---
 mm/kasan/Makefile     |  9 ++++++++-
 mm/kasan/kasan_test.c | 29 +++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile
index d4837bff3b60..7634dd2a6128 100644
--- a/mm/kasan/Makefile
+++ b/mm/kasan/Makefile
@@ -35,7 +35,14 @@ CFLAGS_shadow.o := $(CC_FLAGS_KASAN_RUNTIME)
 CFLAGS_hw_tags.o := $(CC_FLAGS_KASAN_RUNTIME)
 CFLAGS_sw_tags.o := $(CC_FLAGS_KASAN_RUNTIME)
 
-CFLAGS_KASAN_TEST := $(CFLAGS_KASAN) -fno-builtin $(call cc-disable-warning, vla)
+CFLAGS_KASAN_TEST := $(CFLAGS_KASAN) $(call cc-disable-warning, vla)
+ifndef CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX
+# If compiler instruments memintrinsics by prefixing them with __asan/__hwasan,
+# we need to treat them normally (as builtins), otherwise the compiler won't
+# recognize them as instrumentable. If it doesn't instrument them, we need to
+# pass -fno-builtin, so the compiler doesn't inline them.
+CFLAGS_KASAN_TEST += -fno-builtin
+endif
 
 CFLAGS_kasan_test.o := $(CFLAGS_KASAN_TEST)
 CFLAGS_kasan_test_module.o := $(CFLAGS_KASAN_TEST)
diff --git a/mm/kasan/kasan_test.c b/mm/kasan/kasan_test.c
index 74cd80c12b25..627eaf1ee1db 100644
--- a/mm/kasan/kasan_test.c
+++ b/mm/kasan/kasan_test.c
@@ -165,6 +165,15 @@ static void kasan_test_exit(struct kunit *test)
 		kunit_skip((test), "Test requires " #config "=n");	\
 } while (0)
 
+#define KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test) do {		\
+	if (IS_ENABLED(CONFIG_KASAN_HW_TAGS))				\
+		break;  /* No compiler instrumentation. */		\
+	if (IS_ENABLED(CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX))	\
+		break;  /* Should always be instrumented! */		\
+	if (IS_ENABLED(CONFIG_GENERIC_ENTRY))				\
+		kunit_skip((test), "Test requires checked mem*()");	\
+} while (0)
+
 static void kmalloc_oob_right(struct kunit *test)
 {
 	char *ptr;
@@ -454,6 +463,8 @@ static void kmalloc_oob_16(struct kunit *test)
 		u64 words[2];
 	} *ptr1, *ptr2;
 
+	KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test);
+
 	/* This test is specifically crafted for the generic mode. */
 	KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_GENERIC);
 
@@ -476,6 +487,8 @@ static void kmalloc_uaf_16(struct kunit *test)
 		u64 words[2];
 	} *ptr1, *ptr2;
 
+	KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test);
+
 	ptr1 = kmalloc(sizeof(*ptr1), GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr1);
 
@@ -498,6 +511,8 @@ static void kmalloc_oob_memset_2(struct kunit *test)
 	char *ptr;
 	size_t size = 128 - KASAN_GRANULE_SIZE;
 
+	KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test);
+
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
@@ -511,6 +526,8 @@ static void kmalloc_oob_memset_4(struct kunit *test)
 	char *ptr;
 	size_t size = 128 - KASAN_GRANULE_SIZE;
 
+	KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test);
+
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
@@ -524,6 +541,8 @@ static void kmalloc_oob_memset_8(struct kunit *test)
 	char *ptr;
 	size_t size = 128 - KASAN_GRANULE_SIZE;
 
+	KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test);
+
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
@@ -537,6 +556,8 @@ static void kmalloc_oob_memset_16(struct kunit *test)
 	char *ptr;
 	size_t size = 128 - KASAN_GRANULE_SIZE;
 
+	KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test);
+
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
@@ -550,6 +571,8 @@ static void kmalloc_oob_in_memset(struct kunit *test)
 	char *ptr;
 	size_t size = 128 - KASAN_GRANULE_SIZE;
 
+	KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test);
+
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
@@ -566,6 +589,8 @@ static void kmalloc_memmove_negative_size(struct kunit *test)
 	size_t size = 64;
 	size_t invalid_size = -2;
 
+	KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test);
+
 	/*
 	 * Hardware tag-based mode doesn't check memmove for negative size.
 	 * As a result, this test introduces a side-effect memory corruption,
@@ -590,6 +615,8 @@ static void kmalloc_memmove_invalid_size(struct kunit *test)
 	size_t size = 64;
 	size_t invalid_size = size;
 
+	KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test);
+
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
@@ -618,6 +645,8 @@ static void kmalloc_uaf_memset(struct kunit *test)
 	char *ptr;
 	size_t size = 33;
 
+	KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test);
+
 	/*
 	 * Only generic KASAN uses quarantine, which is required to avoid a
 	 * kernel memory corruption this test causes.
-- 
2.39.2.637.g21b0678d19-goog