de5cd8ccd4
Recently, the maps for an elf in memory might show up looking like: f0000-f1000 0 r-- /system/lib/libc.so f1000-f2000 0 --- f2000-f3000 1000 r-x /system/lib/libc.so f3000-f4000 2000 rw- /system/lib/libc.so That empty map was confusing the logic when looking for a global variable. Now this case is handled properly. New unit test added for this case. Bug: 147910661 Test: Ran unit tests. Test: Ran original failing test 137-cfi. Change-Id: Ida2e96d1da5e1bf61f41646949fe5a2d405c0d61
99 lines
3.1 KiB
C++
99 lines
3.1 KiB
C++
/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <stdint.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <string>
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#include <vector>
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#include <unwindstack/Global.h>
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#include <unwindstack/MapInfo.h>
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#include <unwindstack/Maps.h>
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#include <unwindstack/Memory.h>
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namespace unwindstack {
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Global::Global(std::shared_ptr<Memory>& memory) : memory_(memory) {}
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Global::Global(std::shared_ptr<Memory>& memory, std::vector<std::string>& search_libs)
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: memory_(memory), search_libs_(search_libs) {}
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void Global::SetArch(ArchEnum arch) {
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if (arch_ == ARCH_UNKNOWN) {
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arch_ = arch;
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ProcessArch();
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}
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}
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bool Global::Searchable(const std::string& name) {
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if (search_libs_.empty()) {
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return true;
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}
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if (name.empty()) {
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return false;
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}
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const char* base_name = basename(name.c_str());
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for (const std::string& lib : search_libs_) {
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if (base_name == lib) {
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return true;
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}
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}
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return false;
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}
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void Global::FindAndReadVariable(Maps* maps, const char* var_str) {
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std::string variable(var_str);
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// When looking for global variables, do not arbitrarily search every
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// readable map. Instead look for a specific pattern that must exist.
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// The pattern should be a readable map, followed by a read-write
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// map with a non-zero offset.
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// For example:
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// f0000-f1000 0 r-- /system/lib/libc.so
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// f1000-f2000 1000 r-x /system/lib/libc.so
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// f2000-f3000 2000 rw- /system/lib/libc.so
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// This also works:
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// f0000-f2000 0 r-- /system/lib/libc.so
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// f2000-f3000 2000 rw- /system/lib/libc.so
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// It is also possible to see empty maps after the read-only like so:
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// f0000-f1000 0 r-- /system/lib/libc.so
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// f1000-f2000 0 ---
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// f2000-f3000 1000 r-x /system/lib/libc.so
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// f3000-f4000 2000 rw- /system/lib/libc.so
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MapInfo* map_zero = nullptr;
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for (const auto& info : *maps) {
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if (info->offset != 0 && (info->flags & (PROT_READ | PROT_WRITE)) == (PROT_READ | PROT_WRITE) &&
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map_zero != nullptr && Searchable(info->name) && info->name == map_zero->name) {
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Elf* elf = map_zero->GetElf(memory_, arch());
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uint64_t ptr;
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if (elf->GetGlobalVariableOffset(variable, &ptr) && ptr != 0) {
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uint64_t offset_end = info->offset + info->end - info->start;
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if (ptr >= info->offset && ptr < offset_end) {
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ptr = info->start + ptr - info->offset;
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if (ReadVariableData(ptr)) {
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break;
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}
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}
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}
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} else if (info->offset == 0 && !info->name.empty()) {
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map_zero = info.get();
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}
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}
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}
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} // namespace unwindstack
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