kasan: add atomic tests

Test that KASan can detect some unsafe atomic accesses.

As discussed in the linked thread below, these tests attempt to cover
the most common uses of atomics and, therefore, aren't exhaustive.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lore.kernel.org/all/[email protected]/T/#u
Signed-off-by: Paul Heidekrüger <[email protected]>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=214055
Acked-by: Mark Rutland <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Vincenzo Frascino <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 79 insertions, 0 deletions

diff --git a/mm/kasan/kasan_test.c b/mm/kasan/kasan_test.c
index 971cfff4ca0b..318d9cec111a 100644
--- a/mm/kasan/kasan_test.c
+++ b/mm/kasan/kasan_test.c
@@ -697,6 +697,84 @@ static void kmalloc_uaf3(struct kunit *test)
 	KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr1)[8]);
 }
 
+static void kasan_atomics_helper(struct kunit *test, void *unsafe, void *safe)
+{
+	int *i_unsafe = (int *)unsafe;
+
+	KUNIT_EXPECT_KASAN_FAIL(test, READ_ONCE(*i_unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, WRITE_ONCE(*i_unsafe, 42));
+	KUNIT_EXPECT_KASAN_FAIL(test, smp_load_acquire(i_unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, smp_store_release(i_unsafe, 42));
+
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_read(unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_set(unsafe, 42));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_add(42, unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_sub(42, unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_inc(unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_dec(unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_and(42, unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_andnot(42, unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_or(42, unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_xor(42, unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_xchg(unsafe, 42));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_cmpxchg(unsafe, 21, 42));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_try_cmpxchg(unsafe, safe, 42));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_try_cmpxchg(safe, unsafe, 42));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_sub_and_test(42, unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_dec_and_test(unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_inc_and_test(unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_add_negative(42, unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_add_unless(unsafe, 21, 42));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_inc_not_zero(unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_inc_unless_negative(unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_dec_unless_positive(unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_dec_if_positive(unsafe));
+
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_read(unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_set(unsafe, 42));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_add(42, unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_sub(42, unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_inc(unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_dec(unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_and(42, unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_andnot(42, unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_or(42, unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_xor(42, unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_xchg(unsafe, 42));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_cmpxchg(unsafe, 21, 42));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_try_cmpxchg(unsafe, safe, 42));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_try_cmpxchg(safe, unsafe, 42));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_sub_and_test(42, unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_dec_and_test(unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_inc_and_test(unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_add_negative(42, unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_add_unless(unsafe, 21, 42));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_inc_not_zero(unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_inc_unless_negative(unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_dec_unless_positive(unsafe));
+	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_dec_if_positive(unsafe));
+}
+
+static void kasan_atomics(struct kunit *test)
+{
+	void *a1, *a2;
+
+	/*
+	 * Just as with kasan_bitops_tags(), we allocate 48 bytes of memory such
+	 * that the following 16 bytes will make up the redzone.
+	 */
+	a1 = kzalloc(48, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, a1);
+	a2 = kzalloc(sizeof(int), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, a1);
+
+	/* Use atomics to access the redzone. */
+	kasan_atomics_helper(test, a1 + 48, a2);
+
+	kfree(a1);
+	kfree(a2);
+}
+
 static void kmalloc_double_kzfree(struct kunit *test)
 {
 	char *ptr;
@@ -1883,6 +1961,7 @@ static struct kunit_case kasan_kunit_test_cases[] = {
 	KUNIT_CASE(kasan_strings),
 	KUNIT_CASE(kasan_bitops_generic),
 	KUNIT_CASE(kasan_bitops_tags),
+	KUNIT_CASE(kasan_atomics),
 	KUNIT_CASE(vmalloc_helpers_tags),
 	KUNIT_CASE(vmalloc_oob),
 	KUNIT_CASE(vmap_tags),