lsan_common_linux.cc revision 2d1fdb26e458c4ddc04155c1d421bced3ba90cd0
1//=-- lsan_common_linux.cc ------------------------------------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file is a part of LeakSanitizer. 11// Implementation of common leak checking functionality. Linux-specific code. 12// 13//===----------------------------------------------------------------------===// 14 15#include "sanitizer_common/sanitizer_platform.h" 16#include "lsan_common.h" 17 18#if CAN_SANITIZE_LEAKS && SANITIZER_LINUX 19#include <link.h> 20 21#include "sanitizer_common/sanitizer_common.h" 22#include "sanitizer_common/sanitizer_flags.h" 23#include "sanitizer_common/sanitizer_linux.h" 24#include "sanitizer_common/sanitizer_stackdepot.h" 25 26namespace __lsan { 27 28static const char kLinkerName[] = "ld"; 29// We request 2 modules matching "ld", so we can print a warning if there's more 30// than one match. But only the first one is actually used. 31static char linker_placeholder[2 * sizeof(LoadedModule)] ALIGNED(64); 32static LoadedModule *linker = 0; 33 34static bool IsLinker(const char* full_name) { 35 return LibraryNameIs(full_name, kLinkerName); 36} 37 38void InitializePlatformSpecificModules() { 39 internal_memset(linker_placeholder, 0, sizeof(linker_placeholder)); 40 uptr num_matches = GetListOfModules( 41 reinterpret_cast<LoadedModule *>(linker_placeholder), 2, IsLinker); 42 if (num_matches == 1) { 43 linker = reinterpret_cast<LoadedModule *>(linker_placeholder); 44 return; 45 } 46 if (num_matches == 0) 47 VReport(1, "LeakSanitizer: Dynamic linker not found. " 48 "TLS will not be handled correctly.\n"); 49 else if (num_matches > 1) 50 VReport(1, "LeakSanitizer: Multiple modules match \"%s\". " 51 "TLS will not be handled correctly.\n", kLinkerName); 52 linker = 0; 53} 54 55static int ProcessGlobalRegionsCallback(struct dl_phdr_info *info, size_t size, 56 void *data) { 57 Frontier *frontier = reinterpret_cast<Frontier *>(data); 58 for (uptr j = 0; j < info->dlpi_phnum; j++) { 59 const ElfW(Phdr) *phdr = &(info->dlpi_phdr[j]); 60 // We're looking for .data and .bss sections, which reside in writeable, 61 // loadable segments. 62 if (!(phdr->p_flags & PF_W) || (phdr->p_type != PT_LOAD) || 63 (phdr->p_memsz == 0)) 64 continue; 65 uptr begin = info->dlpi_addr + phdr->p_vaddr; 66 uptr end = begin + phdr->p_memsz; 67 uptr allocator_begin = 0, allocator_end = 0; 68 GetAllocatorGlobalRange(&allocator_begin, &allocator_end); 69 if (begin <= allocator_begin && allocator_begin < end) { 70 CHECK_LE(allocator_begin, allocator_end); 71 CHECK_LT(allocator_end, end); 72 if (begin < allocator_begin) 73 ScanRangeForPointers(begin, allocator_begin, frontier, "GLOBAL", 74 kReachable); 75 if (allocator_end < end) 76 ScanRangeForPointers(allocator_end, end, frontier, "GLOBAL", 77 kReachable); 78 } else { 79 ScanRangeForPointers(begin, end, frontier, "GLOBAL", kReachable); 80 } 81 } 82 return 0; 83} 84 85// Scans global variables for heap pointers. 86void ProcessGlobalRegions(Frontier *frontier) { 87 if (!flags()->use_globals) return; 88 // FIXME: dl_iterate_phdr acquires a linker lock, so we run a risk of 89 // deadlocking by running this under StopTheWorld. However, the lock is 90 // reentrant, so we should be able to fix this by acquiring the lock before 91 // suspending threads. 92 dl_iterate_phdr(ProcessGlobalRegionsCallback, frontier); 93} 94 95static uptr GetCallerPC(u32 stack_id, StackDepotReverseMap *map) { 96 CHECK(stack_id); 97 uptr size = 0; 98 const uptr *trace = map->Get(stack_id, &size); 99 // The top frame is our malloc/calloc/etc. The next frame is the caller. 100 if (size >= 2) 101 return trace[1]; 102 return 0; 103} 104 105struct ProcessPlatformAllocParam { 106 Frontier *frontier; 107 StackDepotReverseMap *stack_depot_reverse_map; 108}; 109 110// ForEachChunk callback. Identifies unreachable chunks which must be treated as 111// reachable. Marks them as reachable and adds them to the frontier. 112static void ProcessPlatformSpecificAllocationsCb(uptr chunk, void *arg) { 113 CHECK(arg); 114 ProcessPlatformAllocParam *param = 115 reinterpret_cast<ProcessPlatformAllocParam *>(arg); 116 chunk = GetUserBegin(chunk); 117 LsanMetadata m(chunk); 118 if (m.allocated() && m.tag() != kReachable) { 119 u32 stack_id = m.stack_trace_id(); 120 uptr caller_pc = 0; 121 if (stack_id > 0) 122 caller_pc = GetCallerPC(stack_id, param->stack_depot_reverse_map); 123 // If caller_pc is unknown, this chunk may be allocated in a coroutine. Mark 124 // it as reachable, as we can't properly report its allocation stack anyway. 125 if (caller_pc == 0 || linker->containsAddress(caller_pc)) { 126 m.set_tag(kReachable); 127 param->frontier->push_back(chunk); 128 } 129 } 130} 131 132// Handles dynamically allocated TLS blocks by treating all chunks allocated 133// from ld-linux.so as reachable. 134// Dynamic TLS blocks contain the TLS variables of dynamically loaded modules. 135// They are allocated with a __libc_memalign() call in allocate_and_init() 136// (elf/dl-tls.c). Glibc won't tell us the address ranges occupied by those 137// blocks, but we can make sure they come from our own allocator by intercepting 138// __libc_memalign(). On top of that, there is no easy way to reach them. Their 139// addresses are stored in a dynamically allocated array (the DTV) which is 140// referenced from the static TLS. Unfortunately, we can't just rely on the DTV 141// being reachable from the static TLS, and the dynamic TLS being reachable from 142// the DTV. This is because the initial DTV is allocated before our interception 143// mechanism kicks in, and thus we don't recognize it as allocated memory. We 144// can't special-case it either, since we don't know its size. 145// Our solution is to include in the root set all allocations made from 146// ld-linux.so (which is where allocate_and_init() is implemented). This is 147// guaranteed to include all dynamic TLS blocks (and possibly other allocations 148// which we don't care about). 149void ProcessPlatformSpecificAllocations(Frontier *frontier) { 150 if (!flags()->use_tls) return; 151 if (!linker) return; 152 StackDepotReverseMap stack_depot_reverse_map; 153 ProcessPlatformAllocParam arg = {frontier, &stack_depot_reverse_map}; 154 ForEachChunk(ProcessPlatformSpecificAllocationsCb, &arg); 155} 156 157} // namespace __lsan 158#endif // CAN_SANITIZE_LEAKS && SANITIZER_LINUX 159