On Fri, Feb 2, 2024 at 12:33 PM Paul Heidekrüger <paul.heidekrueger@xxxxxx> wrote: > > 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. > > CC: Marco Elver <elver@xxxxxxxxxx> > CC: Andrey Konovalov <andreyknvl@xxxxxxxxx> > Link: https://lore.kernel.org/all/20240131210041.686657-1-paul.heidekrueger@xxxxxx/T/#u > Closes: https://bugzilla.kernel.org/show_bug.cgi?id=214055 > Signed-off-by: Paul Heidekrüger <paul.heidekrueger@xxxxxx> > --- > Changes PATCH RFC v2 -> PATCH v1: > * Remove casts to void* > * Remove i_safe variable > * Add atomic_long_* test cases > * Carry over comment from kasan_bitops_tags() > > Changes PATCH RFC v1 -> PATCH RFC v2: > * Adjust size of allocations to make kasan_atomics() work with all KASan modes > * Remove comments and move tests closer to the bitops tests > * For functions taking two addresses as an input, test each address in a separate function call. > * Rename variables for clarity > * Add tests for READ_ONCE(), WRITE_ONCE(), smp_load_acquire() and smp_store_release() > > mm/kasan/kasan_test.c | 79 +++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 79 insertions(+) > > diff --git a/mm/kasan/kasan_test.c b/mm/kasan/kasan_test.c > index 8281eb42464b..4ef2280c322c 100644 > --- a/mm/kasan/kasan_test.c > +++ b/mm/kasan/kasan_test.c > @@ -1150,6 +1150,84 @@ static void kasan_bitops_tags(struct kunit *test) > kfree(bits); > } > > +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); I think this should be sizeof(atomic_long_t) or sizeof(long), otherwise a2 will not work as the safe argument for atomic_long_try_cmpxchg on 64-bit architectures. > + 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; > @@ -1553,6 +1631,7 @@ 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(kmalloc_double_kzfree), > KUNIT_CASE(rcu_uaf), > KUNIT_CASE(workqueue_uaf), > -- > 2.40.1 >
