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187 lines
7.2 KiB
187 lines
7.2 KiB
//=-- lsan_common_linux.cc ------------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file is a part of LeakSanitizer.
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// Implementation of common leak checking functionality. Linux-specific code.
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//
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//===----------------------------------------------------------------------===//
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#include "sanitizer_common/sanitizer_platform.h"
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#include "lsan_common.h"
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#if CAN_SANITIZE_LEAKS && SANITIZER_LINUX
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#include <link.h>
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#include "sanitizer_common/sanitizer_common.h"
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#include "sanitizer_common/sanitizer_flags.h"
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#include "sanitizer_common/sanitizer_linux.h"
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#include "sanitizer_common/sanitizer_stackdepot.h"
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namespace __lsan {
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static const char kLinkerName[] = "ld";
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static char linker_placeholder[sizeof(LoadedModule)] ALIGNED(64);
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static LoadedModule *linker = nullptr;
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static bool IsLinker(const char* full_name) {
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return LibraryNameIs(full_name, kLinkerName);
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}
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void InitializePlatformSpecificModules() {
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ListOfModules modules;
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modules.init();
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for (LoadedModule &module : modules) {
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if (!IsLinker(module.full_name())) continue;
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if (linker == nullptr) {
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linker = reinterpret_cast<LoadedModule *>(linker_placeholder);
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*linker = module;
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module = LoadedModule();
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} else {
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VReport(1, "LeakSanitizer: Multiple modules match \"%s\". "
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"TLS will not be handled correctly.\n", kLinkerName);
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linker->clear();
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linker = nullptr;
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return;
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}
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}
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VReport(1, "LeakSanitizer: Dynamic linker not found. "
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"TLS will not be handled correctly.\n");
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}
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static int ProcessGlobalRegionsCallback(struct dl_phdr_info *info, size_t size,
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void *data) {
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Frontier *frontier = reinterpret_cast<Frontier *>(data);
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for (uptr j = 0; j < info->dlpi_phnum; j++) {
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const ElfW(Phdr) *phdr = &(info->dlpi_phdr[j]);
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// We're looking for .data and .bss sections, which reside in writeable,
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// loadable segments.
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if (!(phdr->p_flags & PF_W) || (phdr->p_type != PT_LOAD) ||
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(phdr->p_memsz == 0))
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continue;
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uptr begin = info->dlpi_addr + phdr->p_vaddr;
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uptr end = begin + phdr->p_memsz;
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uptr allocator_begin = 0, allocator_end = 0;
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GetAllocatorGlobalRange(&allocator_begin, &allocator_end);
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if (begin <= allocator_begin && allocator_begin < end) {
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CHECK_LE(allocator_begin, allocator_end);
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CHECK_LT(allocator_end, end);
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if (begin < allocator_begin)
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ScanRangeForPointers(begin, allocator_begin, frontier, "GLOBAL",
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kReachable);
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if (allocator_end < end)
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ScanRangeForPointers(allocator_end, end, frontier, "GLOBAL",
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kReachable);
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} else {
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ScanRangeForPointers(begin, end, frontier, "GLOBAL", kReachable);
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}
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}
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return 0;
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}
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// Scans global variables for heap pointers.
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void ProcessGlobalRegions(Frontier *frontier) {
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if (!flags()->use_globals) return;
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dl_iterate_phdr(ProcessGlobalRegionsCallback, frontier);
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}
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static uptr GetCallerPC(u32 stack_id, StackDepotReverseMap *map) {
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CHECK(stack_id);
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StackTrace stack = map->Get(stack_id);
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// The top frame is our malloc/calloc/etc. The next frame is the caller.
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if (stack.size >= 2)
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return stack.trace[1];
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return 0;
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}
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struct ProcessPlatformAllocParam {
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Frontier *frontier;
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StackDepotReverseMap *stack_depot_reverse_map;
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bool skip_linker_allocations;
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};
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// ForEachChunk callback. Identifies unreachable chunks which must be treated as
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// reachable. Marks them as reachable and adds them to the frontier.
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static void ProcessPlatformSpecificAllocationsCb(uptr chunk, void *arg) {
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CHECK(arg);
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ProcessPlatformAllocParam *param =
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reinterpret_cast<ProcessPlatformAllocParam *>(arg);
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chunk = GetUserBegin(chunk);
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LsanMetadata m(chunk);
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if (m.allocated() && m.tag() != kReachable && m.tag() != kIgnored) {
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u32 stack_id = m.stack_trace_id();
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uptr caller_pc = 0;
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if (stack_id > 0)
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caller_pc = GetCallerPC(stack_id, param->stack_depot_reverse_map);
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// If caller_pc is unknown, this chunk may be allocated in a coroutine. Mark
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// it as reachable, as we can't properly report its allocation stack anyway.
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if (caller_pc == 0 || (param->skip_linker_allocations &&
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linker->containsAddress(caller_pc))) {
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m.set_tag(kReachable);
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param->frontier->push_back(chunk);
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}
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}
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}
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// Handles dynamically allocated TLS blocks by treating all chunks allocated
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// from ld-linux.so as reachable.
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// Dynamic TLS blocks contain the TLS variables of dynamically loaded modules.
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// They are allocated with a __libc_memalign() call in allocate_and_init()
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// (elf/dl-tls.c). Glibc won't tell us the address ranges occupied by those
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// blocks, but we can make sure they come from our own allocator by intercepting
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// __libc_memalign(). On top of that, there is no easy way to reach them. Their
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// addresses are stored in a dynamically allocated array (the DTV) which is
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// referenced from the static TLS. Unfortunately, we can't just rely on the DTV
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// being reachable from the static TLS, and the dynamic TLS being reachable from
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// the DTV. This is because the initial DTV is allocated before our interception
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// mechanism kicks in, and thus we don't recognize it as allocated memory. We
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// can't special-case it either, since we don't know its size.
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// Our solution is to include in the root set all allocations made from
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// ld-linux.so (which is where allocate_and_init() is implemented). This is
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// guaranteed to include all dynamic TLS blocks (and possibly other allocations
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// which we don't care about).
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void ProcessPlatformSpecificAllocations(Frontier *frontier) {
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StackDepotReverseMap stack_depot_reverse_map;
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ProcessPlatformAllocParam arg;
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arg.frontier = frontier;
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arg.stack_depot_reverse_map = &stack_depot_reverse_map;
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arg.skip_linker_allocations =
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flags()->use_tls && flags()->use_ld_allocations && linker != nullptr;
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ForEachChunk(ProcessPlatformSpecificAllocationsCb, &arg);
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}
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struct DoStopTheWorldParam {
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StopTheWorldCallback callback;
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void *argument;
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};
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static int DoStopTheWorldCallback(struct dl_phdr_info *info, size_t size,
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void *data) {
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DoStopTheWorldParam *param = reinterpret_cast<DoStopTheWorldParam *>(data);
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StopTheWorld(param->callback, param->argument);
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return 1;
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}
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// LSan calls dl_iterate_phdr() from the tracer task. This may deadlock: if one
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// of the threads is frozen while holding the libdl lock, the tracer will hang
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// in dl_iterate_phdr() forever.
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// Luckily, (a) the lock is reentrant and (b) libc can't distinguish between the
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// tracer task and the thread that spawned it. Thus, if we run the tracer task
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// while holding the libdl lock in the parent thread, we can safely reenter it
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// in the tracer. The solution is to run stoptheworld from a dl_iterate_phdr()
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// callback in the parent thread.
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void DoStopTheWorld(StopTheWorldCallback callback, void *argument) {
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DoStopTheWorldParam param = {callback, argument};
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dl_iterate_phdr(DoStopTheWorldCallback, ¶m);
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}
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} // namespace __lsan
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#endif // CAN_SANITIZE_LEAKS && SANITIZER_LINUX
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