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lib/test_stackinit: Add assigned initializers
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
1 parent 1e2cd30 commit a8fc576

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Lines changed: 114 additions & 55 deletions

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‎lib/test_stackinit.c‎

Lines changed: 114 additions & 55 deletions
Original file line numberDiff line numberDiff line change
@@ -95,6 +95,10 @@ static bool range_contains(char *haystack_start, size_t haystack_size,
9595
return false;
9696
}
9797

98+
/* Whether the test is expected to fail. */
99+
#define WANT_SUCCESS 0
100+
#define XFAIL 1
101+
98102
#define DO_NOTHING_TYPE_SCALAR(var_type) var_type
99103
#define DO_NOTHING_TYPE_STRING(var_type) void
100104
#define DO_NOTHING_TYPE_STRUCT(var_type) void
@@ -120,34 +124,74 @@ static bool range_contains(char *haystack_start, size_t haystack_size,
120124
#define INIT_CLONE_STRING [FILL_SIZE_STRING]
121125
#define INIT_CLONE_STRUCT /**/
122126

123-
#define INIT_SCALAR_none /**/
124-
#define INIT_SCALAR_zero = 0
127+
#define ZERO_CLONE_SCALAR(zero) memset(&(zero), 0x00, sizeof(zero))
128+
#define ZERO_CLONE_STRING(zero) memset(&(zero), 0x00, sizeof(zero))
129+
/*
130+
* For the struct, intentionally poison padding to see if it gets
131+
* copied out in direct assignments.
132+
* */
133+
#define ZERO_CLONE_STRUCT(zero) \
134+
do { \
135+
memset(&(zero), 0xFF, sizeof(zero)); \
136+
zero.one = 0; \
137+
zero.two = 0; \
138+
zero.three = 0; \
139+
zero.four = 0; \
140+
} while (0)
141+
142+
#define INIT_SCALAR_none(var_type) /**/
143+
#define INIT_SCALAR_zero(var_type) = 0
125144

126-
#define INIT_STRING_none [FILL_SIZE_STRING] /**/
127-
#define INIT_STRING_zero [FILL_SIZE_STRING] = { }
145+
#define INIT_STRING_none(var_type) [FILL_SIZE_STRING] /**/
146+
#define INIT_STRING_zero(var_type) [FILL_SIZE_STRING] = { }
128147

129-
#define INIT_STRUCT_none /**/
130-
#define INIT_STRUCT_zero = { }
131-
#define INIT_STRUCT_static_partial = { .two = 0, }
132-
#define INIT_STRUCT_static_all = { .one = 0, \
133-
.two = 0, \
134-
.three = 0, \
135-
.four = 0, \
148+
#define INIT_STRUCT_none(var_type) /**/
149+
#define INIT_STRUCT_zero(var_type) = { }
150+
151+
152+
#define __static_partial { .two = 0, }
153+
#define __static_all { .one = 0, \
154+
.two = 0, \
155+
.three = 0, \
156+
.four = 0, \
136157
}
137-
#define INIT_STRUCT_dynamic_partial = { .two = arg->two, }
138-
#define INIT_STRUCT_dynamic_all = { .one = arg->one, \
139-
.two = arg->two, \
140-
.three = arg->three, \
141-
.four = arg->four, \
158+
#define __dynamic_partial { .two = arg->two, }
159+
#define __dynamic_all { .one = arg->one, \
160+
.two = arg->two, \
161+
.three = arg->three, \
162+
.four = arg->four, \
142163
}
143-
#define INIT_STRUCT_runtime_partial ; \
144-
var.two = 0
145-
#define INIT_STRUCT_runtime_all ; \
146-
var.one = 0; \
164+
#define __runtime_partial var.two = 0
165+
#define __runtime_all var.one = 0; \
147166
var.two = 0; \
148167
var.three = 0; \
149168
var.four = 0
150169

170+
#define INIT_STRUCT_static_partial(var_type) \
171+
= __static_partial
172+
#define INIT_STRUCT_static_all(var_type) \
173+
= __static_all
174+
#define INIT_STRUCT_dynamic_partial(var_type) \
175+
= __dynamic_partial
176+
#define INIT_STRUCT_dynamic_all(var_type) \
177+
= __dynamic_all
178+
#define INIT_STRUCT_runtime_partial(var_type) \
179+
; __runtime_partial
180+
#define INIT_STRUCT_runtime_all(var_type) \
181+
; __runtime_all
182+
183+
#define INIT_STRUCT_assigned_static_partial(var_type) \
184+
; var = (var_type)__static_partial
185+
#define INIT_STRUCT_assigned_static_all(var_type) \
186+
; var = (var_type)__static_all
187+
#define INIT_STRUCT_assigned_dynamic_partial(var_type) \
188+
; var = (var_type)__dynamic_partial
189+
#define INIT_STRUCT_assigned_dynamic_all(var_type) \
190+
; var = (var_type)__dynamic_all
191+
192+
#define INIT_STRUCT_assigned_copy(var_type) \
193+
; var = *(arg)
194+
151195
/*
152196
* @name: unique string name for the test
153197
* @var_type: type to be tested for zeroing initialization
@@ -167,7 +211,7 @@ static noinline __init int test_ ## name (void) \
167211
BUILD_BUG_ON(sizeof(zero) > MAX_VAR_SIZE); \
168212
\
169213
/* Fill clone type with zero for per-field init. */ \
170-
memset(&zero, 0x00, sizeof(zero)); \
214+
ZERO_CLONE_ ## which(zero); \
171215
/* Clear entire check buffer for 0xFF overlap test. */ \
172216
memset(check_buf, 0x00, sizeof(check_buf)); \
173217
/* Fill stack with 0xFF. */ \
@@ -210,7 +254,7 @@ static noinline __init int test_ ## name (void) \
210254
return (xfail) ? 0 : 1; \
211255
} \
212256
}
213-
#define DEFINE_TEST(name, var_type, which, init_level) \
257+
#define DEFINE_TEST(name, var_type, which, init_level, xfail) \
214258
/* no-op to force compiler into ignoring "uninitialized" vars */\
215259
static noinline __init DO_NOTHING_TYPE_ ## which(var_type) \
216260
do_nothing_ ## name(var_type *ptr) \
@@ -226,7 +270,8 @@ static noinline __init int leaf_ ## name(unsigned long sp, \
226270
var_type *arg) \
227271
{ \
228272
char buf[VAR_BUFFER]; \
229-
var_type var INIT_ ## which ## _ ## init_level; \
273+
var_type var \
274+
INIT_ ## which ## _ ## init_level(var_type); \
230275
\
231276
target_start = &var; \
232277
target_size = sizeof(var); \
@@ -252,7 +297,7 @@ static noinline __init int leaf_ ## name(unsigned long sp, \
252297
\
253298
return (int)buf[0] | (int)buf[sizeof(buf) - 1]; \
254299
} \
255-
DEFINE_TEST_DRIVER(name, var_type, which, 0)
300+
DEFINE_TEST_DRIVER(name, var_type, which, xfail)
256301

257302
/* Structure with no padding. */
258303
struct test_packed {
@@ -296,42 +341,50 @@ struct test_user {
296341
unsigned long four;
297342
};
298343

299-
#define DEFINE_SCALAR_TEST(name, init) \
300-
DEFINE_TEST(name ## _ ## init, name, SCALAR, init)
344+
#define DEFINE_SCALAR_TEST(name, init, xfail) \
345+
DEFINE_TEST(name ## _ ## init, name, SCALAR, \
346+
init, xfail)
301347

302-
#define DEFINE_SCALAR_TESTS(init) \
303-
DEFINE_SCALAR_TEST(u8, init); \
304-
DEFINE_SCALAR_TEST(u16, init); \
305-
DEFINE_SCALAR_TEST(u32, init); \
306-
DEFINE_SCALAR_TEST(u64, init); \
307-
DEFINE_TEST(char_array_ ## init, unsigned char, STRING, init)
348+
#define DEFINE_SCALAR_TESTS(init, xfail) \
349+
DEFINE_SCALAR_TEST(u8, init, xfail); \
350+
DEFINE_SCALAR_TEST(u16, init, xfail); \
351+
DEFINE_SCALAR_TEST(u32, init, xfail); \
352+
DEFINE_SCALAR_TEST(u64, init, xfail); \
353+
DEFINE_TEST(char_array_ ## init, unsigned char, \
354+
STRING, init, xfail)
308355

309-
#define DEFINE_STRUCT_TEST(name, init) \
356+
#define DEFINE_STRUCT_TEST(name, init, xfail) \
310357
DEFINE_TEST(name ## _ ## init, \
311-
struct test_ ## name, STRUCT, init)
358+
struct test_ ## name, STRUCT, init, \
359+
xfail)
360+
361+
#define DEFINE_STRUCT_TESTS(init, xfail) \
362+
DEFINE_STRUCT_TEST(small_hole, init, xfail); \
363+
DEFINE_STRUCT_TEST(big_hole, init, xfail); \
364+
DEFINE_STRUCT_TEST(trailing_hole, init, xfail); \
365+
DEFINE_STRUCT_TEST(packed, init, xfail)
312366

313-
#define DEFINE_STRUCT_TESTS(init) \
314-
DEFINE_STRUCT_TEST(small_hole, init); \
315-
DEFINE_STRUCT_TEST(big_hole, init); \
316-
DEFINE_STRUCT_TEST(trailing_hole, init); \
317-
DEFINE_STRUCT_TEST(packed, init)
367+
#define DEFINE_STRUCT_INITIALIZER_TESTS(base) \
368+
DEFINE_STRUCT_TESTS(base ## _ ## partial, \
369+
WANT_SUCCESS); \
370+
DEFINE_STRUCT_TESTS(base ## _ ## all, \
371+
WANT_SUCCESS)
318372

319373
/* These should be fully initialized all the time! */
320-
DEFINE_SCALAR_TESTS(zero);
321-
DEFINE_STRUCT_TESTS(zero);
322-
/* Static initialization: padding may be left uninitialized. */
323-
DEFINE_STRUCT_TESTS(static_partial);
324-
DEFINE_STRUCT_TESTS(static_all);
325-
/* Dynamic initialization: padding may be left uninitialized. */
326-
DEFINE_STRUCT_TESTS(dynamic_partial);
327-
DEFINE_STRUCT_TESTS(dynamic_all);
328-
/* Runtime initialization: padding may be left uninitialized. */
329-
DEFINE_STRUCT_TESTS(runtime_partial);
330-
DEFINE_STRUCT_TESTS(runtime_all);
374+
DEFINE_SCALAR_TESTS(zero, WANT_SUCCESS);
375+
DEFINE_STRUCT_TESTS(zero, WANT_SUCCESS);
376+
/* Struct initializers: padding may be left uninitialized. */
377+
DEFINE_STRUCT_INITIALIZER_TESTS(static);
378+
DEFINE_STRUCT_INITIALIZER_TESTS(dynamic);
379+
DEFINE_STRUCT_INITIALIZER_TESTS(runtime);
380+
DEFINE_STRUCT_INITIALIZER_TESTS(assigned_static);
381+
DEFINE_STRUCT_INITIALIZER_TESTS(assigned_dynamic);
382+
DEFINE_STRUCT_TESTS(assigned_copy, XFAIL);
331383
/* No initialization without compiler instrumentation. */
332-
DEFINE_SCALAR_TESTS(none);
333-
DEFINE_STRUCT_TESTS(none);
334-
DEFINE_TEST(user, struct test_user, STRUCT, none);
384+
DEFINE_SCALAR_TESTS(none, WANT_SUCCESS);
385+
DEFINE_STRUCT_TESTS(none, WANT_SUCCESS);
386+
/* Initialization of members with __user attribute. */
387+
DEFINE_TEST(user, struct test_user, STRUCT, none, WANT_SUCCESS);
335388

336389
/*
337390
* 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,
394447
* non-code areas (i.e. in a switch statement before the first "case").
395448
* https://bugs.llvm.org/show_bug.cgi?id=44916
396449
*/
397-
DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR, 1);
398-
DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR, 1);
450+
DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR, XFAIL);
451+
DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR, XFAIL);
399452

400453
static int __init test_stackinit_init(void)
401454
{
@@ -421,12 +474,18 @@ static int __init test_stackinit_init(void)
421474
test_structs(zero);
422475
/* Padding here appears to be accidentally always initialized? */
423476
test_structs(dynamic_partial);
477+
test_structs(assigned_dynamic_partial);
424478
/* Padding initialization depends on compiler behaviors. */
425479
test_structs(static_partial);
426480
test_structs(static_all);
427481
test_structs(dynamic_all);
428482
test_structs(runtime_partial);
429483
test_structs(runtime_all);
484+
test_structs(assigned_static_partial);
485+
test_structs(assigned_static_all);
486+
test_structs(assigned_dynamic_all);
487+
/* Everything fails this since it effectively performs a memcpy(). */
488+
test_structs(assigned_copy);
430489

431490
/* STRUCTLEAK_BYREF_ALL should cover everything from here down. */
432491
test_scalars(none);

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