lib/test_stackinit: Add assigned initializers
authorKees Cook <keescook@chromium.org>
Fri, 23 Jul 2021 22:19:33 +0000 (15:19 -0700)
committerKees Cook <keescook@chromium.org>
Sun, 22 Aug 2021 07:21:36 +0000 (00:21 -0700)
Add whole-variable assignments of cast static initializers. These appear
to currently behave like the direct initializers, but best to check them
too. For example:

struct test_big_hole var;
var = (struct test_big_hole){
.one = arg->one,
.two= arg->two,
.three = arg->three,
.four = arg->four };

Additionally adds a test for whole-object assignment, which is expected
to fail since it usually falls back to a memcpy():

var = *arg;

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/lkml/CAK8P3a20SEoYCrp3jOK32oZc9OkiPv+1KTjNZ2GxLbHpY4WexQ@mail.gmail.com
Cc: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210723221933.3431999-4-keescook@chromium.org
lib/test_stackinit.c

index 70bcc1e..a3c74e6 100644 (file)
@@ -95,6 +95,10 @@ static bool range_contains(char *haystack_start, size_t haystack_size,
        return false;
 }
 
+/* Whether the test is expected to fail. */
+#define WANT_SUCCESS                           0
+#define XFAIL                                  1
+
 #define DO_NOTHING_TYPE_SCALAR(var_type)       var_type
 #define DO_NOTHING_TYPE_STRING(var_type)       void
 #define DO_NOTHING_TYPE_STRUCT(var_type)       void
@@ -120,34 +124,74 @@ static bool range_contains(char *haystack_start, size_t haystack_size,
 #define INIT_CLONE_STRING              [FILL_SIZE_STRING]
 #define INIT_CLONE_STRUCT              /**/
 
-#define INIT_SCALAR_none               /**/
-#define INIT_SCALAR_zero               = 0
+#define ZERO_CLONE_SCALAR(zero)                memset(&(zero), 0x00, sizeof(zero))
+#define ZERO_CLONE_STRING(zero)                memset(&(zero), 0x00, sizeof(zero))
+/*
+ * For the struct, intentionally poison padding to see if it gets
+ * copied out in direct assignments.
+ * */
+#define ZERO_CLONE_STRUCT(zero)                                \
+       do {                                            \
+               memset(&(zero), 0xFF, sizeof(zero));    \
+               zero.one = 0;                           \
+               zero.two = 0;                           \
+               zero.three = 0;                         \
+               zero.four = 0;                          \
+       } while (0)
+
+#define INIT_SCALAR_none(var_type)     /**/
+#define INIT_SCALAR_zero(var_type)     = 0
 
-#define INIT_STRING_none               [FILL_SIZE_STRING] /**/
-#define INIT_STRING_zero               [FILL_SIZE_STRING] = { }
+#define INIT_STRING_none(var_type)     [FILL_SIZE_STRING] /**/
+#define INIT_STRING_zero(var_type)     [FILL_SIZE_STRING] = { }
 
-#define INIT_STRUCT_none               /**/
-#define INIT_STRUCT_zero               = { }
-#define INIT_STRUCT_static_partial     = { .two = 0, }
-#define INIT_STRUCT_static_all         = { .one = 0,                   \
-                                           .two = 0,                   \
-                                           .three = 0,                 \
-                                           .four = 0,                  \
+#define INIT_STRUCT_none(var_type)     /**/
+#define INIT_STRUCT_zero(var_type)     = { }
+
+
+#define __static_partial               { .two = 0, }
+#define __static_all                   { .one = 0,                     \
+                                         .two = 0,                     \
+                                         .three = 0,                   \
+                                         .four = 0,                    \
                                        }
-#define INIT_STRUCT_dynamic_partial    = { .two = arg->two, }
-#define INIT_STRUCT_dynamic_all                = { .one = arg->one,            \
-                                           .two = arg->two,            \
-                                           .three = arg->three,        \
-                                           .four = arg->four,          \
+#define __dynamic_partial              { .two = arg->two, }
+#define __dynamic_all                  { .one = arg->one,              \
+                                         .two = arg->two,              \
+                                         .three = arg->three,          \
+                                         .four = arg->four,            \
                                        }
-#define INIT_STRUCT_runtime_partial    ;                               \
-                                       var.two = 0
-#define INIT_STRUCT_runtime_all                ;                               \
-                                       var.one = 0;                    \
+#define __runtime_partial              var.two = 0
+#define __runtime_all                  var.one = 0;                    \
                                        var.two = 0;                    \
                                        var.three = 0;                  \
                                        var.four = 0
 
+#define INIT_STRUCT_static_partial(var_type)                           \
+                                       = __static_partial
+#define INIT_STRUCT_static_all(var_type)                               \
+                                       = __static_all
+#define INIT_STRUCT_dynamic_partial(var_type)                          \
+                                       = __dynamic_partial
+#define INIT_STRUCT_dynamic_all(var_type)                              \
+                                       = __dynamic_all
+#define INIT_STRUCT_runtime_partial(var_type)                          \
+                                       ; __runtime_partial
+#define INIT_STRUCT_runtime_all(var_type)                              \
+                                       ; __runtime_all
+
+#define INIT_STRUCT_assigned_static_partial(var_type)                  \
+                                       ; var = (var_type)__static_partial
+#define INIT_STRUCT_assigned_static_all(var_type)                      \
+                                       ; var = (var_type)__static_all
+#define INIT_STRUCT_assigned_dynamic_partial(var_type)                 \
+                                       ; var = (var_type)__dynamic_partial
+#define INIT_STRUCT_assigned_dynamic_all(var_type)                     \
+                                       ; var = (var_type)__dynamic_all
+
+#define INIT_STRUCT_assigned_copy(var_type)                            \
+                                       ; var = *(arg)
+
 /*
  * @name: unique string name for the test
  * @var_type: type to be tested for zeroing initialization
@@ -167,7 +211,7 @@ static noinline __init int test_ ## name (void)                     \
        BUILD_BUG_ON(sizeof(zero) > MAX_VAR_SIZE);              \
                                                                \
        /* Fill clone type with zero for per-field init. */     \
-       memset(&zero, 0x00, sizeof(zero));                      \
+       ZERO_CLONE_ ## which(zero);                             \
        /* Clear entire check buffer for 0xFF overlap test. */  \
        memset(check_buf, 0x00, sizeof(check_buf));             \
        /* Fill stack with 0xFF. */                             \
@@ -210,7 +254,7 @@ static noinline __init int test_ ## name (void)                     \
                return (xfail) ? 0 : 1;                         \
        }                                                       \
 }
-#define DEFINE_TEST(name, var_type, which, init_level)         \
+#define DEFINE_TEST(name, var_type, which, init_level, xfail)  \
 /* no-op to force compiler into ignoring "uninitialized" vars */\
 static noinline __init DO_NOTHING_TYPE_ ## which(var_type)     \
 do_nothing_ ## name(var_type *ptr)                             \
@@ -226,7 +270,8 @@ static noinline __init int leaf_ ## name(unsigned long sp,  \
                                         var_type *arg)         \
 {                                                              \
        char buf[VAR_BUFFER];                                   \
-       var_type var INIT_ ## which ## _ ## init_level;         \
+       var_type var                                            \
+               INIT_ ## which ## _ ## init_level(var_type);    \
                                                                \
        target_start = &var;                                    \
        target_size = sizeof(var);                              \
@@ -252,7 +297,7 @@ static noinline __init int leaf_ ## name(unsigned long sp,  \
                                                                \
        return (int)buf[0] | (int)buf[sizeof(buf) - 1];         \
 }                                                              \
-DEFINE_TEST_DRIVER(name, var_type, which, 0)
+DEFINE_TEST_DRIVER(name, var_type, which, xfail)
 
 /* Structure with no padding. */
 struct test_packed {
@@ -296,42 +341,50 @@ struct test_user {
        unsigned long four;
 };
 
-#define DEFINE_SCALAR_TEST(name, init)                         \
-               DEFINE_TEST(name ## _ ## init, name, SCALAR, init)
+#define DEFINE_SCALAR_TEST(name, init, xfail)                  \
+               DEFINE_TEST(name ## _ ## init, name, SCALAR,    \
+                           init, xfail)
 
-#define DEFINE_SCALAR_TESTS(init)                              \
-               DEFINE_SCALAR_TEST(u8, init);                   \
-               DEFINE_SCALAR_TEST(u16, init);                  \
-               DEFINE_SCALAR_TEST(u32, init);                  \
-               DEFINE_SCALAR_TEST(u64, init);                  \
-               DEFINE_TEST(char_array_ ## init, unsigned char, STRING, init)
+#define DEFINE_SCALAR_TESTS(init, xfail)                       \
+               DEFINE_SCALAR_TEST(u8, init, xfail);            \
+               DEFINE_SCALAR_TEST(u16, init, xfail);           \
+               DEFINE_SCALAR_TEST(u32, init, xfail);           \
+               DEFINE_SCALAR_TEST(u64, init, xfail);           \
+               DEFINE_TEST(char_array_ ## init, unsigned char, \
+                           STRING, init, xfail)
 
-#define DEFINE_STRUCT_TEST(name, init)                         \
+#define DEFINE_STRUCT_TEST(name, init, xfail)                  \
                DEFINE_TEST(name ## _ ## init,                  \
-                           struct test_ ## name, STRUCT, init)
+                           struct test_ ## name, STRUCT, init, \
+                           xfail)
+
+#define DEFINE_STRUCT_TESTS(init, xfail)                       \
+               DEFINE_STRUCT_TEST(small_hole, init, xfail);    \
+               DEFINE_STRUCT_TEST(big_hole, init, xfail);      \
+               DEFINE_STRUCT_TEST(trailing_hole, init, xfail); \
+               DEFINE_STRUCT_TEST(packed, init, xfail)
 
-#define DEFINE_STRUCT_TESTS(init)                              \
-               DEFINE_STRUCT_TEST(small_hole, init);           \
-               DEFINE_STRUCT_TEST(big_hole, init);             \
-               DEFINE_STRUCT_TEST(trailing_hole, init);        \
-               DEFINE_STRUCT_TEST(packed, init)
+#define DEFINE_STRUCT_INITIALIZER_TESTS(base)                  \
+               DEFINE_STRUCT_TESTS(base ## _ ## partial,       \
+                                   WANT_SUCCESS);              \
+               DEFINE_STRUCT_TESTS(base ## _ ## all,           \
+                                   WANT_SUCCESS)
 
 /* These should be fully initialized all the time! */
-DEFINE_SCALAR_TESTS(zero);
-DEFINE_STRUCT_TESTS(zero);
-/* Static initialization: padding may be left uninitialized. */
-DEFINE_STRUCT_TESTS(static_partial);
-DEFINE_STRUCT_TESTS(static_all);
-/* Dynamic initialization: padding may be left uninitialized. */
-DEFINE_STRUCT_TESTS(dynamic_partial);
-DEFINE_STRUCT_TESTS(dynamic_all);
-/* Runtime initialization: padding may be left uninitialized. */
-DEFINE_STRUCT_TESTS(runtime_partial);
-DEFINE_STRUCT_TESTS(runtime_all);
+DEFINE_SCALAR_TESTS(zero, WANT_SUCCESS);
+DEFINE_STRUCT_TESTS(zero, WANT_SUCCESS);
+/* Struct initializers: padding may be left uninitialized. */
+DEFINE_STRUCT_INITIALIZER_TESTS(static);
+DEFINE_STRUCT_INITIALIZER_TESTS(dynamic);
+DEFINE_STRUCT_INITIALIZER_TESTS(runtime);
+DEFINE_STRUCT_INITIALIZER_TESTS(assigned_static);
+DEFINE_STRUCT_INITIALIZER_TESTS(assigned_dynamic);
+DEFINE_STRUCT_TESTS(assigned_copy, XFAIL);
 /* No initialization without compiler instrumentation. */
-DEFINE_SCALAR_TESTS(none);
-DEFINE_STRUCT_TESTS(none);
-DEFINE_TEST(user, struct test_user, STRUCT, none);
+DEFINE_SCALAR_TESTS(none, WANT_SUCCESS);
+DEFINE_STRUCT_TESTS(none, WANT_SUCCESS);
+/* Initialization of members with __user attribute. */
+DEFINE_TEST(user, struct test_user, STRUCT, none, WANT_SUCCESS);
 
 /*
  * Check two uses through a variable declaration outside either path,
@@ -394,8 +447,8 @@ static noinline __init int leaf_switch_2_none(unsigned long sp, bool fill,
  * non-code areas (i.e. in a switch statement before the first "case").
  * https://bugs.llvm.org/show_bug.cgi?id=44916
  */
-DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR, 1);
-DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR, 1);
+DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR, XFAIL);
+DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR, XFAIL);
 
 static int __init test_stackinit_init(void)
 {
@@ -421,12 +474,18 @@ static int __init test_stackinit_init(void)
        test_structs(zero);
        /* Padding here appears to be accidentally always initialized? */
        test_structs(dynamic_partial);
+       test_structs(assigned_dynamic_partial);
        /* Padding initialization depends on compiler behaviors. */
        test_structs(static_partial);
        test_structs(static_all);
        test_structs(dynamic_all);
        test_structs(runtime_partial);
        test_structs(runtime_all);
+       test_structs(assigned_static_partial);
+       test_structs(assigned_static_all);
+       test_structs(assigned_dynamic_all);
+       /* Everything fails this since it effectively performs a memcpy(). */
+       test_structs(assigned_copy);
 
        /* STRUCTLEAK_BYREF_ALL should cover everything from here down. */
        test_scalars(none);