1 //===-- MemoryHistoryASan.cpp ---------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "MemoryHistoryASan.h"
10 
11 #include "lldb/Target/MemoryHistory.h"
12 
13 #include "Plugins/Process/Utility/HistoryThread.h"
14 #include "lldb/Core/Debugger.h"
15 #include "lldb/Core/Module.h"
16 #include "lldb/Core/PluginInterface.h"
17 #include "lldb/Core/PluginManager.h"
18 #include "lldb/Core/ValueObject.h"
19 #include "lldb/Expression/UserExpression.h"
20 #include "lldb/Target/ExecutionContext.h"
21 #include "lldb/Target/Target.h"
22 #include "lldb/Target/Thread.h"
23 #include "lldb/Target/ThreadList.h"
24 #include "lldb/lldb-private.h"
25 
26 #include <sstream>
27 
28 using namespace lldb;
29 using namespace lldb_private;
30 
31 LLDB_PLUGIN_DEFINE(MemoryHistoryASan)
32 
33 MemoryHistorySP MemoryHistoryASan::CreateInstance(const ProcessSP &process_sp) {
34   if (!process_sp.get())
35     return nullptr;
36 
37   Target &target = process_sp->GetTarget();
38 
39   for (ModuleSP module_sp : target.GetImages().Modules()) {
40     const Symbol *symbol = module_sp->FindFirstSymbolWithNameAndType(
41         ConstString("__asan_get_alloc_stack"), lldb::eSymbolTypeAny);
42 
43     if (symbol != nullptr)
44       return MemoryHistorySP(new MemoryHistoryASan(process_sp));
45   }
46 
47   return MemoryHistorySP();
48 }
49 
50 void MemoryHistoryASan::Initialize() {
51   PluginManager::RegisterPlugin(
52       GetPluginNameStatic(), "ASan memory history provider.", CreateInstance);
53 }
54 
55 void MemoryHistoryASan::Terminate() {
56   PluginManager::UnregisterPlugin(CreateInstance);
57 }
58 
59 MemoryHistoryASan::MemoryHistoryASan(const ProcessSP &process_sp) {
60   if (process_sp)
61     m_process_wp = process_sp;
62 }
63 
64 const char *memory_history_asan_command_prefix = R"(
65     extern "C"
66     {
67         size_t __asan_get_alloc_stack(void *addr, void **trace, size_t size, int *thread_id);
68         size_t __asan_get_free_stack(void *addr, void **trace, size_t size, int *thread_id);
69     }
70 )";
71 
72 const char *memory_history_asan_command_format =
73     R"(
74     struct {
75         void *alloc_trace[256];
76         size_t alloc_count;
77         int alloc_tid;
78 
79         void *free_trace[256];
80         size_t free_count;
81         int free_tid;
82     } t;
83 
84     t.alloc_count = __asan_get_alloc_stack((void *)0x%)" PRIx64
85     R"(, t.alloc_trace, 256, &t.alloc_tid);
86     t.free_count = __asan_get_free_stack((void *)0x%)" PRIx64
87     R"(, t.free_trace, 256, &t.free_tid);
88 
89     t;
90 )";
91 
92 static void CreateHistoryThreadFromValueObject(ProcessSP process_sp,
93                                                ValueObjectSP return_value_sp,
94                                                const char *type,
95                                                const char *thread_name,
96                                                HistoryThreads &result) {
97   std::string count_path = "." + std::string(type) + "_count";
98   std::string tid_path = "." + std::string(type) + "_tid";
99   std::string trace_path = "." + std::string(type) + "_trace";
100 
101   ValueObjectSP count_sp =
102       return_value_sp->GetValueForExpressionPath(count_path.c_str());
103   ValueObjectSP tid_sp =
104       return_value_sp->GetValueForExpressionPath(tid_path.c_str());
105 
106   if (!count_sp || !tid_sp)
107     return;
108 
109   int count = count_sp->GetValueAsUnsigned(0);
110   tid_t tid = tid_sp->GetValueAsUnsigned(0) + 1;
111 
112   if (count <= 0)
113     return;
114 
115   ValueObjectSP trace_sp =
116       return_value_sp->GetValueForExpressionPath(trace_path.c_str());
117 
118   if (!trace_sp)
119     return;
120 
121   std::vector<lldb::addr_t> pcs;
122   for (int i = 0; i < count; i++) {
123     addr_t pc = trace_sp->GetChildAtIndex(i)->GetValueAsUnsigned(0);
124     if (pc == 0 || pc == 1 || pc == LLDB_INVALID_ADDRESS)
125       continue;
126     pcs.push_back(pc);
127   }
128 
129   // The ASAN runtime already massages the return addresses into call
130   // addresses, we don't want LLDB's unwinder to try to locate the previous
131   // instruction again as this might lead to us reporting a different line.
132   bool pcs_are_call_addresses = true;
133   HistoryThread *history_thread =
134       new HistoryThread(*process_sp, tid, pcs, pcs_are_call_addresses);
135   ThreadSP new_thread_sp(history_thread);
136   std::ostringstream thread_name_with_number;
137   thread_name_with_number << thread_name << " Thread " << tid;
138   history_thread->SetThreadName(thread_name_with_number.str().c_str());
139   // Save this in the Process' ExtendedThreadList so a strong pointer retains
140   // the object
141   process_sp->GetExtendedThreadList().AddThread(new_thread_sp);
142   result.push_back(new_thread_sp);
143 }
144 
145 HistoryThreads MemoryHistoryASan::GetHistoryThreads(lldb::addr_t address) {
146   HistoryThreads result;
147 
148   ProcessSP process_sp = m_process_wp.lock();
149   if (!process_sp)
150     return result;
151 
152   ThreadSP thread_sp =
153       process_sp->GetThreadList().GetExpressionExecutionThread();
154   if (!thread_sp)
155     return result;
156 
157   StackFrameSP frame_sp =
158       thread_sp->GetSelectedFrame(DoNoSelectMostRelevantFrame);
159   if (!frame_sp)
160     return result;
161 
162   ExecutionContext exe_ctx(frame_sp);
163   ValueObjectSP return_value_sp;
164   StreamString expr;
165   Status eval_error;
166   expr.Printf(memory_history_asan_command_format, address, address);
167 
168   EvaluateExpressionOptions options;
169   options.SetUnwindOnError(true);
170   options.SetTryAllThreads(true);
171   options.SetStopOthers(true);
172   options.SetIgnoreBreakpoints(true);
173   options.SetTimeout(process_sp->GetUtilityExpressionTimeout());
174   options.SetPrefix(memory_history_asan_command_prefix);
175   options.SetAutoApplyFixIts(false);
176   options.SetLanguage(eLanguageTypeObjC_plus_plus);
177 
178   ExpressionResults expr_result = UserExpression::Evaluate(
179       exe_ctx, options, expr.GetString(), "", return_value_sp, eval_error);
180   if (expr_result != eExpressionCompleted) {
181     StreamString ss;
182     ss << "cannot evaluate AddressSanitizer expression:\n";
183     ss << eval_error.AsCString();
184     Debugger::ReportWarning(ss.GetString().str(),
185                             process_sp->GetTarget().GetDebugger().GetID());
186     return result;
187   }
188 
189   if (!return_value_sp)
190     return result;
191 
192   CreateHistoryThreadFromValueObject(process_sp, return_value_sp, "free",
193                                      "Memory deallocated by", result);
194   CreateHistoryThreadFromValueObject(process_sp, return_value_sp, "alloc",
195                                      "Memory allocated by", result);
196 
197   return result;
198 }
199