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//=-- lsan_common_linux.cpp -----------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file is a part of LeakSanitizer.
// Implementation of common leak checking functionality. Linux/NetBSD-specific
// code.
//
//===----------------------------------------------------------------------===//
#include "sanitizer_common/sanitizer_platform.h"
#include "lsan_common.h"
#if CAN_SANITIZE_LEAKS && (SANITIZER_LINUX || SANITIZER_NETBSD)
#include <link.h>
#include "sanitizer_common/sanitizer_common.h"
#include "sanitizer_common/sanitizer_flags.h"
#include "sanitizer_common/sanitizer_getauxval.h"
#include "sanitizer_common/sanitizer_linux.h"
#include "sanitizer_common/sanitizer_stackdepot.h"
namespace __lsan {
static const char kLinkerName[] = "ld";
static char linker_placeholder[sizeof(LoadedModule)] ALIGNED(64);
static LoadedModule *linker = nullptr;
static bool IsLinker(const LoadedModule& module) {
#if SANITIZER_USE_GETAUXVAL
return module.base_address() == getauxval(AT_BASE);
#else
return LibraryNameIs(module.full_name(), kLinkerName);
#endif // SANITIZER_USE_GETAUXVAL
}
__attribute__((tls_model("initial-exec")))
THREADLOCAL int disable_counter;
bool DisabledInThisThread() { return disable_counter > 0; }
void DisableInThisThread() { disable_counter++; }
void EnableInThisThread() {
if (disable_counter == 0) {
DisableCounterUnderflow();
}
disable_counter--;
}
void InitializePlatformSpecificModules() {
ListOfModules modules;
modules.init();
for (LoadedModule &module : modules) {
if (!IsLinker(module))
continue;
if (linker == nullptr) {
linker = reinterpret_cast<LoadedModule *>(linker_placeholder);
*linker = module;
module = LoadedModule();
} else {
VReport(1, "LeakSanitizer: Multiple modules match \"%s\". "
"TLS and other allocations originating from linker might be "
"falsely reported as leaks.\n", kLinkerName);
linker->clear();
linker = nullptr;
return;
}
}
if (linker == nullptr) {
VReport(1, "LeakSanitizer: Dynamic linker not found. TLS and other "
"allocations originating from linker might be falsely reported "
"as leaks.\n");
}
}
static int ProcessGlobalRegionsCallback(struct dl_phdr_info *info, size_t size,
void *data) {
Frontier *frontier = reinterpret_cast<Frontier *>(data);
for (uptr j = 0; j < info->dlpi_phnum; j++) {
const ElfW(Phdr) *phdr = &(info->dlpi_phdr[j]);
// We're looking for .data and .bss sections, which reside in writeable,
// loadable segments.
if (!(phdr->p_flags & PF_W) || (phdr->p_type != PT_LOAD) ||
(phdr->p_memsz == 0))
continue;
uptr begin = info->dlpi_addr + phdr->p_vaddr;
uptr end = begin + phdr->p_memsz;
ScanGlobalRange(begin, end, frontier);
}
return 0;
}
#if SANITIZER_ANDROID && __ANDROID_API__ < 21
extern "C" __attribute__((weak)) int dl_iterate_phdr(
int (*)(struct dl_phdr_info *, size_t, void *), void *);
#endif
// Scans global variables for heap pointers.
void ProcessGlobalRegions(Frontier *frontier) {
if (!flags()->use_globals) return;
dl_iterate_phdr(ProcessGlobalRegionsCallback, frontier);
}
LoadedModule *GetLinker() { return linker; }
void ProcessPlatformSpecificAllocations(Frontier *frontier) {}
struct DoStopTheWorldParam {
StopTheWorldCallback callback;
void *argument;
};
// While calling Die() here is undefined behavior and can potentially
// cause race conditions, it isn't possible to intercept exit on linux,
// so we have no choice but to call Die() from the atexit handler.
void HandleLeaks() {
if (common_flags()->exitcode) Die();
}
static int LockStuffAndStopTheWorldCallback(struct dl_phdr_info *info,
size_t size, void *data) {
ScopedStopTheWorldLock lock;
DoStopTheWorldParam *param = reinterpret_cast<DoStopTheWorldParam *>(data);
StopTheWorld(param->callback, param->argument);
return 1;
}
// LSan calls dl_iterate_phdr() from the tracer task. This may deadlock: if one
// of the threads is frozen while holding the libdl lock, the tracer will hang
// in dl_iterate_phdr() forever.
// Luckily, (a) the lock is reentrant and (b) libc can't distinguish between the
// tracer task and the thread that spawned it. Thus, if we run the tracer task
// while holding the libdl lock in the parent thread, we can safely reenter it
// in the tracer. The solution is to run stoptheworld from a dl_iterate_phdr()
// callback in the parent thread.
void LockStuffAndStopTheWorld(StopTheWorldCallback callback,
CheckForLeaksParam *argument) {
DoStopTheWorldParam param = {callback, argument};
dl_iterate_phdr(LockStuffAndStopTheWorldCallback, ¶m);
}
} // namespace __lsan
#endif
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