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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#include <kunit/test.h>#include <linux/init.h>#include <linux/kernel.h>#include <linux/module.h>#include <linux/string.h>
/* Exfiltration buffer. */#define MAX_VAR_SIZE 128static u8 check_buf[MAX_VAR_SIZE];
/* Character array to trigger stack protector in all functions. */#define VAR_BUFFER 32
/* Volatile mask to convince compiler to copy memory with 0xff. */static volatile u8 forced_mask = 0xff;
/* Location and size tracking to validate fill and test are colocated. */static void *fill_start, *target_start;static size_t fill_size, target_size;
static bool stackinit_range_contains(char *haystack_start, size_t haystack_size, char *needle_start, size_t needle_size){ if (needle_start >= haystack_start && needle_start + needle_size <= haystack_start + haystack_size) return true; 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#define DO_NOTHING_TYPE_UNION(var_type) void
#define DO_NOTHING_RETURN_SCALAR(ptr) *(ptr)#define DO_NOTHING_RETURN_STRING(ptr) /**/#define DO_NOTHING_RETURN_STRUCT(ptr) /**/#define DO_NOTHING_RETURN_UNION(ptr) /**/
#define DO_NOTHING_CALL_SCALAR(var, name) \ (var) = do_nothing_ ## name(&(var))#define DO_NOTHING_CALL_STRING(var, name) \ do_nothing_ ## name(var)#define DO_NOTHING_CALL_STRUCT(var, name) \ do_nothing_ ## name(&(var))#define DO_NOTHING_CALL_UNION(var, name) \ do_nothing_ ## name(&(var))
#define FETCH_ARG_SCALAR(var) &var#define FETCH_ARG_STRING(var) var#define FETCH_ARG_STRUCT(var) &var#define FETCH_ARG_UNION(var) &var
/* * On m68k, if the leaf function test variable is longer than 8 bytes, * the start of the stack frame moves. 8 is sufficiently large to * test m68k char arrays, but leave it at 16 for other architectures. */#ifdef CONFIG_M68K#define FILL_SIZE_STRING 8#define FILL_SIZE_ARRAY 2#else#define FILL_SIZE_STRING 16#define FILL_SIZE_ARRAY 8#endif
#define INIT_CLONE_SCALAR /**/#define INIT_CLONE_STRING [FILL_SIZE_STRING]#define INIT_CLONE_STRUCT /**/#define INIT_CLONE_UNION /**/
#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 ZERO_CLONE_UNION(zero) ZERO_CLONE_STRUCT(zero)
#define INIT_SCALAR_none(var_type) /**/#define INIT_SCALAR_zero(var_type) = 0
#define INIT_STRING_none(var_type) [FILL_SIZE_STRING] /**/#define INIT_STRING_zero(var_type) [FILL_SIZE_STRING] = { }
#define INIT_STRUCT_none(var_type) /**/#define INIT_STRUCT_zero(var_type) = { }#define INIT_STRUCT_old_zero(var_type) = { 0 }
#define __static_partial { .two = 0, }#define __static_all { .one = 0, \ .two = 0, \ .three = 0, \ .four = 0, \ }#define __dynamic_partial { .two = arg->two, }#define __dynamic_all { .one = arg->one, \ .two = arg->two, \ .three = arg->three, \ .four = arg->four, \ }#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)
/* Union initialization is the same as structs. */#define INIT_UNION_none(var_type) INIT_STRUCT_none(var_type)#define INIT_UNION_zero(var_type) INIT_STRUCT_zero(var_type)#define INIT_UNION_old_zero(var_type) INIT_STRUCT_old_zero(var_type)
#define INIT_UNION_static_partial(var_type) \ INIT_STRUCT_static_partial(var_type)#define INIT_UNION_static_all(var_type) \ INIT_STRUCT_static_all(var_type)#define INIT_UNION_dynamic_partial(var_type) \ INIT_STRUCT_dynamic_partial(var_type)#define INIT_UNION_dynamic_all(var_type) \ INIT_STRUCT_dynamic_all(var_type)#define INIT_UNION_runtime_partial(var_type) \ INIT_STRUCT_runtime_partial(var_type)#define INIT_UNION_runtime_all(var_type) \ INIT_STRUCT_runtime_all(var_type)#define INIT_UNION_assigned_static_partial(var_type) \ INIT_STRUCT_assigned_static_partial(var_type)#define INIT_UNION_assigned_static_all(var_type) \ INIT_STRUCT_assigned_static_all(var_type)#define INIT_UNION_assigned_dynamic_partial(var_type) \ INIT_STRUCT_assigned_dynamic_partial(var_type)#define INIT_UNION_assigned_dynamic_all(var_type) \ INIT_STRUCT_assigned_dynamic_all(var_type)#define INIT_UNION_assigned_copy(var_type) \ INIT_STRUCT_assigned_copy(var_type)
/* * The "did we actually fill the stack?" check value needs * to be neither 0 nor any of the "pattern" bytes. The * pattern bytes are compiler, architecture, and type based, * so we have to pick a value that never appears for those * combinations. Use 0x99 which is not 0xFF, 0xFE, nor 0xAA. */#define FILL_BYTE 0x99
/* * @name: unique string name for the test * @var_type: type to be tested for zeroing initialization * @which: is this a SCALAR, STRING, or STRUCT type? * @init_level: what kind of initialization is performed * @xfail: is this test expected to fail? */#define DEFINE_TEST_DRIVER(name, var_type, which, xfail) \/* Returns 0 on success, 1 on failure. */ \static noinline void test_ ## name (struct kunit *test) \{ \ var_type zero INIT_CLONE_ ## which; \ int ignored; \ u8 sum = 0, i; \ \ /* Notice when a new test is larger than expected. */ \ BUILD_BUG_ON(sizeof(zero) > MAX_VAR_SIZE); \ \ /* Fill clone type with zero for per-field init. */ \ ZERO_CLONE_ ## which(zero); \ /* Clear entire check buffer for 0xFF overlap test. */ \ memset(check_buf, 0x00, sizeof(check_buf)); \ /* Fill stack with FILL_BYTE. */ \ ignored = leaf_ ##name((unsigned long)&ignored, 1, \ FETCH_ARG_ ## which(zero)); \ /* Verify all bytes overwritten with FILL_BYTE. */ \ for (sum = 0, i = 0; i < target_size; i++) \ sum += (check_buf[i] != FILL_BYTE); \ /* Clear entire check buffer for later bit tests. */ \ memset(check_buf, 0x00, sizeof(check_buf)); \ /* Extract stack-defined variable contents. */ \ ignored = leaf_ ##name((unsigned long)&ignored, 0, \ FETCH_ARG_ ## which(zero)); \ /* \ * Delay the sum test to here to do as little as \ * possible between the two leaf function calls. \ */ \ KUNIT_ASSERT_EQ_MSG(test, sum, 0, \ "leaf fill was not 0x%02X!?\n", \ FILL_BYTE); \ \ /* Validate that compiler lined up fill and target. */ \ KUNIT_ASSERT_TRUE_MSG(test, \ stackinit_range_contains(fill_start, fill_size, \ target_start, target_size), \ "stackframe was not the same between calls!? " \ "(fill %zu wide, target offset by %d)\n", \ fill_size, \ (int)((ssize_t)(uintptr_t)fill_start - \ (ssize_t)(uintptr_t)target_start)); \ \ /* Validate check region has no FILL_BYTE bytes. */ \ for (sum = 0, i = 0; i < target_size; i++) \ sum += (check_buf[i] == FILL_BYTE); \ \ if (sum != 0 && xfail) \ kunit_skip(test, \ "XFAIL uninit bytes: %d\n", \ sum); \ KUNIT_ASSERT_EQ_MSG(test, sum, 0, \ "uninit bytes: %d\n", sum); \}#define DEFINE_TEST(name, var_type, which, init_level, xfail) \/* no-op to force compiler into ignoring "uninitialized" vars */\static noinline DO_NOTHING_TYPE_ ## which(var_type) \do_nothing_ ## name(var_type *ptr) \{ \ OPTIMIZER_HIDE_VAR(ptr); \ /* Will always be true, but compiler doesn't know. */ \ if ((unsigned long)ptr > 0x2) \ return DO_NOTHING_RETURN_ ## which(ptr); \ else \ return DO_NOTHING_RETURN_ ## which(ptr + 1); \} \static noinline int leaf_ ## name(unsigned long sp, bool fill, \ var_type *arg) \{ \ char buf[VAR_BUFFER]; \ var_type var \ INIT_ ## which ## _ ## init_level(var_type); \ \ target_start = &var; \ target_size = sizeof(var); \ /* \ * Keep this buffer around to make sure we've got a \ * stack frame of SOME kind... \ */ \ memset(buf, (char)(sp & 0xff), sizeof(buf)); \ /* Fill variable with FILL_BYTE. */ \ if (fill) { \ fill_start = &var; \ fill_size = sizeof(var); \ memset(fill_start, \ FILL_BYTE & forced_mask, \ fill_size); \ } \ \ /* Silence "never initialized" warnings. */ \ DO_NOTHING_CALL_ ## which(var, name); \ \ /* Exfiltrate "var". */ \ memcpy(check_buf, target_start, target_size); \ \ return (int)buf[0] | (int)buf[sizeof(buf) - 1]; \} \DEFINE_TEST_DRIVER(name, var_type, which, xfail)
/* Structure with no padding. */struct test_packed { unsigned long one; unsigned long two; unsigned long three; unsigned long four;};
/* Simple structure with padding likely to be covered by compiler. */struct test_small_hole { size_t one; char two; /* 3 byte padding hole here. */ int three; unsigned long four;};
/* Trigger unhandled padding in a structure. */struct test_big_hole { u8 one; u8 two; u8 three; /* 61 byte padding hole here. */ u8 four __aligned(64);} __aligned(64);
struct test_trailing_hole { char *one; char *two; char *three; char four; /* "sizeof(unsigned long) - 1" byte padding hole here. */};
/* Test if STRUCTLEAK is clearing structs with __user fields. */struct test_user { u8 one; unsigned long two; char __user *three; unsigned long four;};
/* No padding: all members are the same size. */union test_same_sizes { unsigned long one; unsigned long two; unsigned long three; unsigned long four;};
/* Mismatched sizes, with one and two being small */union test_small_start { char one:1; char two; short three; unsigned long four; struct big_struct { unsigned long array[FILL_SIZE_ARRAY]; } big;};
/* Mismatched sizes, with three and four being small */union test_small_end { short one; unsigned long two; char three:1; char four;};
#define ALWAYS_PASS WANT_SUCCESS#define ALWAYS_FAIL XFAIL
#ifdef CONFIG_INIT_STACK_NONE# define USER_PASS XFAIL# define BYREF_PASS XFAIL# define STRONG_PASS XFAIL#else# define USER_PASS WANT_SUCCESS# define BYREF_PASS WANT_SUCCESS# define STRONG_PASS WANT_SUCCESS#endif
#define DEFINE_SCALAR_TEST(name, init, xfail) \ DEFINE_TEST(name ## _ ## init, name, SCALAR, \ init, xfail)
#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, xfail) \ DEFINE_TEST(name ## _ ## init, \ struct test_ ## name, STRUCT, init, \ xfail)
#define DEFINE_UNION_TEST(name, init, xfail) \ DEFINE_TEST(name ## _ ## init, \ union 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_INITIALIZER_TESTS(base, xfail) \ DEFINE_STRUCT_TESTS(base ## _ ## partial, \ xfail); \ DEFINE_STRUCT_TESTS(base ## _ ## all, xfail)
#define DEFINE_UNION_INITIALIZER_TESTS(base, xfail) \ DEFINE_UNION_TESTS(base ## _ ## partial, \ xfail); \ DEFINE_UNION_TESTS(base ## _ ## all, xfail)
#define DEFINE_UNION_TESTS(init, xfail) \ DEFINE_UNION_TEST(same_sizes, init, xfail); \ DEFINE_UNION_TEST(small_start, init, xfail); \ DEFINE_UNION_TEST(small_end, init, xfail);
/* These should be fully initialized all the time! */DEFINE_SCALAR_TESTS(zero, ALWAYS_PASS);DEFINE_STRUCT_TESTS(zero, ALWAYS_PASS);DEFINE_STRUCT_TESTS(old_zero, ALWAYS_PASS);DEFINE_UNION_TESTS(zero, ALWAYS_PASS);DEFINE_UNION_TESTS(old_zero, ALWAYS_PASS);/* Struct initializers: padding may be left uninitialized. */DEFINE_STRUCT_INITIALIZER_TESTS(static, STRONG_PASS);DEFINE_STRUCT_INITIALIZER_TESTS(dynamic, STRONG_PASS);DEFINE_STRUCT_INITIALIZER_TESTS(runtime, STRONG_PASS);DEFINE_STRUCT_INITIALIZER_TESTS(assigned_static, STRONG_PASS);DEFINE_STRUCT_INITIALIZER_TESTS(assigned_dynamic, STRONG_PASS);DEFINE_STRUCT_TESTS(assigned_copy, ALWAYS_FAIL);DEFINE_UNION_INITIALIZER_TESTS(static, STRONG_PASS);DEFINE_UNION_INITIALIZER_TESTS(dynamic, STRONG_PASS);DEFINE_UNION_INITIALIZER_TESTS(runtime, STRONG_PASS);DEFINE_UNION_INITIALIZER_TESTS(assigned_static, STRONG_PASS);DEFINE_UNION_INITIALIZER_TESTS(assigned_dynamic, STRONG_PASS);DEFINE_UNION_TESTS(assigned_copy, ALWAYS_FAIL);/* No initialization without compiler instrumentation. */DEFINE_SCALAR_TESTS(none, STRONG_PASS);DEFINE_STRUCT_TESTS(none, BYREF_PASS);/* Initialization of members with __user attribute. */DEFINE_TEST(user, struct test_user, STRUCT, none, USER_PASS);
/* * Check two uses through a variable declaration outside either path, * which was noticed as a special case in porting earlier stack init * compiler logic. */static int noinline __leaf_switch_none(int path, bool fill){ switch (path) { /* * This is intentionally unreachable. To silence the * warning, build with -Wno-switch-unreachable */ uint64_t var[10];
case 1: target_start = &var; target_size = sizeof(var); if (fill) { fill_start = &var; fill_size = sizeof(var);
memset(fill_start, (forced_mask | 0x55) & FILL_BYTE, fill_size); } memcpy(check_buf, target_start, target_size); break; case 2: target_start = &var; target_size = sizeof(var); if (fill) { fill_start = &var; fill_size = sizeof(var);
memset(fill_start, (forced_mask | 0xaa) & FILL_BYTE, fill_size); } memcpy(check_buf, target_start, target_size); break; default: var[1] = 5; return var[1] & forced_mask; } return 0;}
static noinline int leaf_switch_1_none(unsigned long sp, bool fill, uint64_t *arg){ return __leaf_switch_none(1, fill);}
static noinline int leaf_switch_2_none(unsigned long sp, bool fill, uint64_t *arg){ return __leaf_switch_none(2, fill);}
/* * These are expected to fail for most configurations because neither * GCC nor Clang have a way to perform initialization of variables in * non-code areas (i.e. in a switch statement before the first "case"). * https://llvm.org/pr44916 */DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR, ALWAYS_FAIL);DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR, ALWAYS_FAIL);
#define KUNIT_test_scalars(init) \ KUNIT_CASE(test_u8_ ## init), \ KUNIT_CASE(test_u16_ ## init), \ KUNIT_CASE(test_u32_ ## init), \ KUNIT_CASE(test_u64_ ## init), \ KUNIT_CASE(test_char_array_ ## init)
#define KUNIT_test_structs(init) \ KUNIT_CASE(test_small_hole_ ## init), \ KUNIT_CASE(test_big_hole_ ## init), \ KUNIT_CASE(test_trailing_hole_ ## init),\ KUNIT_CASE(test_packed_ ## init) \
#define KUNIT_test_unions(init) \ KUNIT_CASE(test_same_sizes_ ## init), \ KUNIT_CASE(test_small_start_ ## init), \ KUNIT_CASE(test_small_end_ ## init) \
static struct kunit_case stackinit_test_cases[] = { /* These are explicitly initialized and should always pass. */ KUNIT_test_scalars(zero), KUNIT_test_structs(zero), KUNIT_test_structs(old_zero), KUNIT_test_unions(zero), KUNIT_test_unions(old_zero), /* Padding here appears to be accidentally always initialized? */ KUNIT_test_structs(dynamic_partial), KUNIT_test_structs(assigned_dynamic_partial), KUNIT_test_unions(dynamic_partial), KUNIT_test_unions(assigned_dynamic_partial), /* Padding initialization depends on compiler behaviors. */ KUNIT_test_structs(static_partial), KUNIT_test_structs(static_all), KUNIT_test_structs(dynamic_all), KUNIT_test_structs(runtime_partial), KUNIT_test_structs(runtime_all), KUNIT_test_structs(assigned_static_partial), KUNIT_test_structs(assigned_static_all), KUNIT_test_structs(assigned_dynamic_all), KUNIT_test_unions(static_partial), KUNIT_test_unions(static_all), KUNIT_test_unions(dynamic_all), KUNIT_test_unions(runtime_partial), KUNIT_test_unions(runtime_all), KUNIT_test_unions(assigned_static_partial), KUNIT_test_unions(assigned_static_all), KUNIT_test_unions(assigned_dynamic_all), /* Everything fails this since it effectively performs a memcpy(). */ KUNIT_test_structs(assigned_copy), KUNIT_test_unions(assigned_copy), /* STRUCTLEAK_BYREF_ALL should cover everything from here down. */ KUNIT_test_scalars(none), KUNIT_CASE(test_switch_1_none), KUNIT_CASE(test_switch_2_none), /* STRUCTLEAK_BYREF should cover from here down. */ KUNIT_test_structs(none), /* STRUCTLEAK will only cover this. */ KUNIT_CASE(test_user), {}};
static struct kunit_suite stackinit_test_suite = { .name = "stackinit", .test_cases = stackinit_test_cases,};
kunit_test_suites(&stackinit_test_suite);
MODULE_DESCRIPTION("Test cases for compiler-based stack variable zeroing");MODULE_LICENSE("GPL");