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//===-- msan.cc -----------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a part of MemorySanitizer.
//
// MemorySanitizer runtime.
//===----------------------------------------------------------------------===//
#include "msan.h"
#include "sanitizer_common/sanitizer_atomic.h"
#include "sanitizer_common/sanitizer_common.h"
#include "sanitizer_common/sanitizer_flags.h"
#include "sanitizer_common/sanitizer_libc.h"
#include "sanitizer_common/sanitizer_procmaps.h"
#include "sanitizer_common/sanitizer_stacktrace.h"
#include "sanitizer_common/sanitizer_symbolizer.h"
#include "interception/interception.h"
// ACHTUNG! No system header includes in this file.
using namespace __sanitizer;
// Globals.
static THREADLOCAL int msan_expect_umr = 0;
static THREADLOCAL int msan_expected_umr_found = 0;
static int msan_running_under_dr = 0;
SANITIZER_INTERFACE_ATTRIBUTE
THREADLOCAL u64 __msan_param_tls[kMsanParamTlsSizeInWords];
SANITIZER_INTERFACE_ATTRIBUTE
THREADLOCAL u32 __msan_param_origin_tls[kMsanParamTlsSizeInWords];
SANITIZER_INTERFACE_ATTRIBUTE
THREADLOCAL u64 __msan_retval_tls[kMsanRetvalTlsSizeInWords];
SANITIZER_INTERFACE_ATTRIBUTE
THREADLOCAL u32 __msan_retval_origin_tls;
SANITIZER_INTERFACE_ATTRIBUTE
THREADLOCAL u64 __msan_va_arg_tls[kMsanParamTlsSizeInWords];
SANITIZER_INTERFACE_ATTRIBUTE
THREADLOCAL u64 __msan_va_arg_overflow_size_tls;
SANITIZER_INTERFACE_ATTRIBUTE
THREADLOCAL u32 __msan_origin_tls;
static THREADLOCAL struct {
uptr stack_top, stack_bottom;
} __msan_stack_bounds;
static THREADLOCAL int is_in_symbolizer;
static THREADLOCAL int is_in_loader;
extern "C" SANITIZER_WEAK_ATTRIBUTE const int __msan_track_origins;
int __msan_get_track_origins() {
return &__msan_track_origins ? __msan_track_origins : 0;
}
extern "C" SANITIZER_WEAK_ATTRIBUTE const int __msan_keep_going;
namespace __msan {
static bool IsRunningUnderDr() {
bool result = false;
MemoryMappingLayout proc_maps(/*cache_enabled*/true);
const sptr kBufSize = 4095;
char *filename = (char*)MmapOrDie(kBufSize, __FUNCTION__);
while (proc_maps.Next(/* start */0, /* end */0, /* file_offset */0,
filename, kBufSize, /* protection */0)) {
if (internal_strstr(filename, "libdynamorio") != 0) {
result = true;
break;
}
}
UnmapOrDie(filename, kBufSize);
return result;
}
void EnterSymbolizer() { ++is_in_symbolizer; }
void ExitSymbolizer() { --is_in_symbolizer; }
bool IsInSymbolizer() { return is_in_symbolizer; }
void EnterLoader() { ++is_in_loader; }
void ExitLoader() { --is_in_loader; }
extern "C" {
SANITIZER_INTERFACE_ATTRIBUTE
bool __msan_is_in_loader() { return is_in_loader; }
}
static Flags msan_flags;
Flags *flags() {
return &msan_flags;
}
int msan_inited = 0;
bool msan_init_is_running;
int msan_report_count = 0;
// Array of stack origins.
// FIXME: make it resizable.
static const uptr kNumStackOriginDescrs = 1024 * 1024;
static const char *StackOriginDescr[kNumStackOriginDescrs];
static uptr StackOriginPC[kNumStackOriginDescrs];
static atomic_uint32_t NumStackOriginDescrs;
static void ParseFlagsFromString(Flags *f, const char *str) {
ParseCommonFlagsFromString(str);
ParseFlag(str, &f->poison_heap_with_zeroes, "poison_heap_with_zeroes");
ParseFlag(str, &f->poison_stack_with_zeroes, "poison_stack_with_zeroes");
ParseFlag(str, &f->poison_in_malloc, "poison_in_malloc");
ParseFlag(str, &f->poison_in_malloc, "poison_in_free");
ParseFlag(str, &f->exit_code, "exit_code");
if (f->exit_code < 0 || f->exit_code > 127) {
Printf("Exit code not in [0, 128) range: %d\n", f->exit_code);
Die();
}
ParseFlag(str, &f->report_umrs, "report_umrs");
ParseFlag(str, &f->wrap_signals, "wrap_signals");
// keep_going is an old name for halt_on_error,
// and it has inverse meaning.
f->halt_on_error = !f->halt_on_error;
ParseFlag(str, &f->halt_on_error, "keep_going");
f->halt_on_error = !f->halt_on_error;
ParseFlag(str, &f->halt_on_error, "halt_on_error");
}
static void InitializeFlags(Flags *f, const char *options) {
CommonFlags *cf = common_flags();
cf->external_symbolizer_path = GetEnv("MSAN_SYMBOLIZER_PATH");
cf->strip_path_prefix = "";
cf->fast_unwind_on_fatal = false;
cf->fast_unwind_on_malloc = true;
cf->malloc_context_size = 20;
cf->handle_ioctl = true;
cf->log_path = 0;
internal_memset(f, 0, sizeof(*f));
f->poison_heap_with_zeroes = false;
f->poison_stack_with_zeroes = false;
f->poison_in_malloc = true;
f->poison_in_free = true;
f->exit_code = 77;
f->report_umrs = true;
f->wrap_signals = true;
f->halt_on_error = !&__msan_keep_going;
// Override from user-specified string.
if (__msan_default_options)
ParseFlagsFromString(f, __msan_default_options());
ParseFlagsFromString(f, options);
}
static void GetCurrentStackBounds(uptr *stack_top, uptr *stack_bottom) {
if (__msan_stack_bounds.stack_top == 0) {
// Break recursion (GetStackTrace -> GetThreadStackTopAndBottom ->
// realloc -> GetStackTrace).
__msan_stack_bounds.stack_top = __msan_stack_bounds.stack_bottom = 1;
GetThreadStackTopAndBottom(/* at_initialization */false,
&__msan_stack_bounds.stack_top,
&__msan_stack_bounds.stack_bottom);
}
*stack_top = __msan_stack_bounds.stack_top;
*stack_bottom = __msan_stack_bounds.stack_bottom;
}
void GetStackTrace(StackTrace *stack, uptr max_s, uptr pc, uptr bp,
bool fast) {
if (!fast) {
// Block reports from our interceptors during _Unwind_Backtrace.
SymbolizerScope sym_scope;
return stack->SlowUnwindStack(pc, max_s);
}
uptr stack_top, stack_bottom;
GetCurrentStackBounds(&stack_top, &stack_bottom);
stack->FastUnwindStack(pc, bp, stack_top, stack_bottom, max_s);
}
void PrintWarning(uptr pc, uptr bp) {
PrintWarningWithOrigin(pc, bp, __msan_origin_tls);
}
bool OriginIsValid(u32 origin) {
return origin != 0 && origin != (u32)-1;
}
void PrintWarningWithOrigin(uptr pc, uptr bp, u32 origin) {
if (msan_expect_umr) {
// Printf("Expected UMR\n");
__msan_origin_tls = origin;
msan_expected_umr_found = 1;
return;
}
++msan_report_count;
StackTrace stack;
GetStackTrace(&stack, kStackTraceMax, pc, bp,
common_flags()->fast_unwind_on_fatal);
u32 report_origin =
(__msan_get_track_origins() && OriginIsValid(origin)) ? origin : 0;
ReportUMR(&stack, report_origin);
if (__msan_get_track_origins() && !OriginIsValid(origin)) {
Printf(
" ORIGIN: invalid (%x). Might be a bug in MemorySanitizer origin "
"tracking.\n This could still be a bug in your code, too!\n",
origin);
}
}
void UnpoisonParam(uptr n) {
internal_memset(__msan_param_tls, 0, n * sizeof(*__msan_param_tls));
}
// Backup MSan runtime TLS state.
// Implementation must be async-signal-safe.
// Instances of this class may live on the signal handler stack, and data size
// may be an issue.
void ScopedThreadLocalStateBackup::Backup() {
va_arg_overflow_size_tls = __msan_va_arg_overflow_size_tls;
}
void ScopedThreadLocalStateBackup::Restore() {
// A lame implementation that only keeps essential state and resets the rest.
__msan_va_arg_overflow_size_tls = va_arg_overflow_size_tls;
internal_memset(__msan_param_tls, 0, sizeof(__msan_param_tls));
internal_memset(__msan_retval_tls, 0, sizeof(__msan_retval_tls));
internal_memset(__msan_va_arg_tls, 0, sizeof(__msan_va_arg_tls));
if (__msan_get_track_origins()) {
internal_memset(&__msan_retval_origin_tls, 0, sizeof(__msan_retval_tls));
internal_memset(__msan_param_origin_tls, 0,
sizeof(__msan_param_origin_tls));
}
}
void UnpoisonThreadLocalState() {
}
const char *GetOriginDescrIfStack(u32 id, uptr *pc) {
if ((id >> 31) == 0) return 0;
id &= (1U << 31) - 1;
CHECK_LT(id, kNumStackOriginDescrs);
if (pc) *pc = StackOriginPC[id];
return StackOriginDescr[id];
}
} // namespace __msan
// Interface.
using namespace __msan;
void __msan_warning() {
GET_CALLER_PC_BP_SP;
(void)sp;
PrintWarning(pc, bp);
if (__msan::flags()->halt_on_error) {
Printf("Exiting\n");
Die();
}
}
void __msan_warning_noreturn() {
GET_CALLER_PC_BP_SP;
(void)sp;
PrintWarning(pc, bp);
Printf("Exiting\n");
Die();
}
void __msan_init() {
if (msan_inited) return;
msan_init_is_running = 1;
SanitizerToolName = "MemorySanitizer";
SetDieCallback(MsanDie);
InitTlsSize();
InitializeInterceptors();
InstallAtExitHandler(); // Needs __cxa_atexit interceptor.
if (MSAN_REPLACE_OPERATORS_NEW_AND_DELETE)
ReplaceOperatorsNewAndDelete();
const char *msan_options = GetEnv("MSAN_OPTIONS");
InitializeFlags(&msan_flags, msan_options);
__sanitizer_set_report_path(common_flags()->log_path);
if (StackSizeIsUnlimited()) {
if (common_flags()->verbosity)
Printf("Unlimited stack, doing reexec\n");
// A reasonably large stack size. It is bigger than the usual 8Mb, because,
// well, the program could have been run with unlimited stack for a reason.
SetStackSizeLimitInBytes(32 * 1024 * 1024);
ReExec();
}
if (common_flags()->verbosity)
Printf("MSAN_OPTIONS: %s\n", msan_options ? msan_options : "<empty>");
msan_running_under_dr = IsRunningUnderDr();
__msan_clear_on_return();
if (__msan_get_track_origins() && common_flags()->verbosity > 0)
Printf("msan_track_origins\n");
if (!InitShadow(/* prot1 */ false, /* prot2 */ true, /* map_shadow */ true,
__msan_get_track_origins())) {
// FIXME: prot1 = false is only required when running under DR.
Printf("FATAL: MemorySanitizer can not mmap the shadow memory.\n");
Printf("FATAL: Make sure to compile with -fPIE and to link with -pie.\n");
Printf("FATAL: Disabling ASLR is known to cause this error.\n");
Printf("FATAL: If running under GDB, try "
"'set disable-randomization off'.\n");
DumpProcessMap();
Die();
}
const char *external_symbolizer = common_flags()->external_symbolizer_path;
bool symbolizer_started =
getSymbolizer()->InitializeExternal(external_symbolizer);
if (external_symbolizer && external_symbolizer[0]) {
CHECK(symbolizer_started);
}
GetThreadStackTopAndBottom(/* at_initialization */true,
&__msan_stack_bounds.stack_top,
&__msan_stack_bounds.stack_bottom);
if (common_flags()->verbosity)
Printf("MemorySanitizer init done\n");
msan_init_is_running = 0;
msan_inited = 1;
}
void __msan_set_exit_code(int exit_code) {
flags()->exit_code = exit_code;
}
void __msan_set_keep_going(int keep_going) {
flags()->halt_on_error = !keep_going;
}
void __msan_set_expect_umr(int expect_umr) {
if (expect_umr) {
msan_expected_umr_found = 0;
} else if (!msan_expected_umr_found) {
GET_CALLER_PC_BP_SP;
(void)sp;
StackTrace stack;
GetStackTrace(&stack, kStackTraceMax, pc, bp,
common_flags()->fast_unwind_on_fatal);
ReportExpectedUMRNotFound(&stack);
Die();
}
msan_expect_umr = expect_umr;
}
void __msan_print_shadow(const void *x, uptr size) {
unsigned char *s = (unsigned char*)MEM_TO_SHADOW(x);
u32 *o = (u32*)MEM_TO_ORIGIN(x);
for (uptr i = 0; i < size; i++) {
Printf("%x%x ", s[i] >> 4, s[i] & 0xf);
}
Printf("\n");
if (__msan_get_track_origins()) {
for (uptr i = 0; i < size / 4; i++) {
Printf(" o: %x ", o[i]);
}
Printf("\n");
}
}
void __msan_print_param_shadow() {
for (int i = 0; i < 16; i++) {
Printf("#%d:%zx ", i, __msan_param_tls[i]);
}
Printf("\n");
}
sptr __msan_test_shadow(const void *x, uptr size) {
unsigned char *s = (unsigned char*)MEM_TO_SHADOW((uptr)x);
for (uptr i = 0; i < size; ++i)
if (s[i])
return i;
return -1;
}
int __msan_set_poison_in_malloc(int do_poison) {
int old = flags()->poison_in_malloc;
flags()->poison_in_malloc = do_poison;
return old;
}
int __msan_has_dynamic_component() {
return msan_running_under_dr;
}
NOINLINE
void __msan_clear_on_return() {
__msan_param_tls[0] = 0;
}
static void* get_tls_base() {
u64 p;
asm("mov %%fs:0, %0"
: "=r"(p) ::);
return (void*)p;
}
int __msan_get_retval_tls_offset() {
// volatile here is needed to avoid UB, because the compiler thinks that we
// are doing address arithmetics on unrelated pointers, and takes some
// shortcuts
volatile sptr retval_tls_p = (sptr)&__msan_retval_tls;
volatile sptr tls_base_p = (sptr)get_tls_base();
return retval_tls_p - tls_base_p;
}
int __msan_get_param_tls_offset() {
// volatile here is needed to avoid UB, because the compiler thinks that we
// are doing address arithmetics on unrelated pointers, and takes some
// shortcuts
volatile sptr param_tls_p = (sptr)&__msan_param_tls;
volatile sptr tls_base_p = (sptr)get_tls_base();
return param_tls_p - tls_base_p;
}
void __msan_partial_poison(const void* data, void* shadow, uptr size) {
internal_memcpy((void*)MEM_TO_SHADOW((uptr)data), shadow, size);
}
void __msan_load_unpoisoned(void *src, uptr size, void *dst) {
internal_memcpy(dst, src, size);
__msan_unpoison(dst, size);
}
void __msan_set_origin(const void *a, uptr size, u32 origin) {
// Origin mapping is 4 bytes per 4 bytes of application memory.
// Here we extend the range such that its left and right bounds are both
// 4 byte aligned.
if (!__msan_get_track_origins()) return;
uptr x = MEM_TO_ORIGIN((uptr)a);
uptr beg = x & ~3UL; // align down.
uptr end = (x + size + 3) & ~3UL; // align up.
u64 origin64 = ((u64)origin << 32) | origin;
// This is like memset, but the value is 32-bit. We unroll by 2 two write
// 64-bits at once. May want to unroll further to get 128-bit stores.
if (beg & 7ULL) {
*(u32*)beg = origin;
beg += 4;
}
for (uptr addr = beg; addr < (end & ~7UL); addr += 8)
*(u64*)addr = origin64;
if (end & 7ULL)
*(u32*)(end - 4) = origin;
}
// 'descr' is created at compile time and contains '----' in the beginning.
// When we see descr for the first time we replace '----' with a uniq id
// and set the origin to (id | (31-th bit)).
void __msan_set_alloca_origin(void *a, uptr size, const char *descr) {
__msan_set_alloca_origin4(a, size, descr, 0);
}
void __msan_set_alloca_origin4(void *a, uptr size, const char *descr, uptr pc) {
static const u32 dash = '-';
static const u32 first_timer =
dash + (dash << 8) + (dash << 16) + (dash << 24);
u32 *id_ptr = (u32*)descr;
bool print = false; // internal_strstr(descr + 4, "AllocaTOTest") != 0;
u32 id = *id_ptr;
if (id == first_timer) {
id = atomic_fetch_add(&NumStackOriginDescrs,
1, memory_order_relaxed);
*id_ptr = id;
CHECK_LT(id, kNumStackOriginDescrs);
StackOriginDescr[id] = descr + 4;
StackOriginPC[id] = pc;
if (print)
Printf("First time: id=%d %s %p \n", id, descr + 4, pc);
}
id |= 1U << 31;
if (print)
Printf("__msan_set_alloca_origin: descr=%s id=%x\n", descr + 4, id);
__msan_set_origin(a, size, id);
}
const char *__msan_get_origin_descr_if_stack(u32 id) {
return GetOriginDescrIfStack(id, 0);
}
u32 __msan_get_origin(const void *a) {
if (!__msan_get_track_origins()) return 0;
uptr x = (uptr)a;
uptr aligned = x & ~3ULL;
uptr origin_ptr = MEM_TO_ORIGIN(aligned);
return *(u32*)origin_ptr;
}
u32 __msan_get_umr_origin() {
return __msan_origin_tls;
}
u16 __sanitizer_unaligned_load16(const uu16 *p) {
__msan_retval_tls[0] = *(uu16 *)MEM_TO_SHADOW((uptr)p);
if (__msan_get_track_origins())
__msan_retval_origin_tls = *(uu32 *)MEM_TO_ORIGIN((uptr)p);
return *p;
}
u32 __sanitizer_unaligned_load32(const uu32 *p) {
__msan_retval_tls[0] = *(uu32 *)MEM_TO_SHADOW((uptr)p);
if (__msan_get_track_origins())
__msan_retval_origin_tls = *(uu32 *)MEM_TO_ORIGIN((uptr)p);
return *p;
}
u64 __sanitizer_unaligned_load64(const uu64 *p) {
__msan_retval_tls[0] = *(uu64 *)MEM_TO_SHADOW((uptr)p);
if (__msan_get_track_origins())
__msan_retval_origin_tls = *(uu32 *)MEM_TO_ORIGIN((uptr)p);
return *p;
}
void __sanitizer_unaligned_store16(uu16 *p, u16 x) {
*(uu16 *)MEM_TO_SHADOW((uptr)p) = __msan_param_tls[1];
if (__msan_get_track_origins())
*(uu32 *)MEM_TO_ORIGIN((uptr)p) = __msan_param_origin_tls[1];
*p = x;
}
void __sanitizer_unaligned_store32(uu32 *p, u32 x) {
*(uu32 *)MEM_TO_SHADOW((uptr)p) = __msan_param_tls[1];
if (__msan_get_track_origins())
*(uu32 *)MEM_TO_ORIGIN((uptr)p) = __msan_param_origin_tls[1];
*p = x;
}
void __sanitizer_unaligned_store64(uu64 *p, u64 x) {
*(uu64 *)MEM_TO_SHADOW((uptr)p) = __msan_param_tls[1];
if (__msan_get_track_origins())
*(uu32 *)MEM_TO_ORIGIN((uptr)p) = __msan_param_origin_tls[1];
*p = x;
}
#if !SANITIZER_SUPPORTS_WEAK_HOOKS
extern "C" {
SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
const char* __msan_default_options() { return ""; }
} // extern "C"
#endif