[tsan] Add some NULL pointer checks into the debugging API

[kubamracek]

Summary

__tsan_get_report_thread and others can crash if a stack trace is missing, let's add the missing checks.

[glider]

lib/tsan/rtl/tsan_debugging.cc

89 ↗

(On Diff #51136)

Do you want to return 0 in the case stack was a nullptr?

[glider]

compiler-rt/trunk/lib/tsan/rtl/tsan_debugging.cc

105

Obviously, my question related to every API function that copies traces ;)

[kubamracek]

compiler-rt/trunk/lib/tsan/rtl/tsan_debugging.cc

105

Hm, I think there are situations when a stack trace is missing, but the rest of the output data is still valid. I think we should still return a success even when the trace is not available. The above (__tsan_get_report_stack) is different, since it *only* returns a stack trace...

[glider]

compiler-rt/trunk/lib/tsan/rtl/tsan_debugging.cc

105

Ok, fair enough.

compiler-rt/trunk/lib/tsan/rtl/tsan_debugging.cc

 }
 
 SANITIZER_INTERFACE_ATTRIBUTE
 int __tsan_get_report_stack(void *report, uptr idx, void **trace,
                             uptr trace_size) {
   const ReportDesc *rep = (ReportDesc *)report;
   CHECK_LT(idx, rep->stacks.Size());
   ReportStack *stack = rep->stacks[idx];
-  CopyTrace(stack->frames, trace, trace_size);
-  return 1;
+  if (stack) CopyTrace(stack->frames, trace, trace_size);
+  return stack ? 1 : 0;
 }
 
 SANITIZER_INTERFACE_ATTRIBUTE
 int __tsan_get_report_mop(void *report, uptr idx, int *tid, void **addr,
                           int *size, int *write, int *atomic, void **trace,
                           uptr trace_size) {
   const ReportDesc *rep = (ReportDesc *)report;
   CHECK_LT(idx, rep->mops.Size());
   ReportMop *mop = rep->mops[idx];
   *tid = mop->tid;
   *addr = (void *)mop->addr;
   *size = mop->size;
   *write = mop->write ? 1 : 0;
   *atomic = mop->atomic ? 1 : 0;
-  CopyTrace(mop->stack->frames, trace, trace_size);
+  if (mop->stack) CopyTrace(mop->stack->frames, trace, trace_size);
   return 1;
 }
 
 SANITIZER_INTERFACE_ATTRIBUTE
 int __tsan_get_report_loc(void *report, uptr idx, const char **type,
                           void **addr, uptr *start, uptr *size, int *tid,
                           int *fd, int *suppressable, void **trace,
                           uptr trace_size) {

 int __tsan_get_report_mutex(void *report, uptr idx, uptr *mutex_id, void **addr,
                             int *destroyed, void **trace, uptr trace_size) {
   const ReportDesc *rep = (ReportDesc *)report;
   CHECK_LT(idx, rep->mutexes.Size());
   ReportMutex *mutex = rep->mutexes[idx];
   *mutex_id = mutex->id;
   *addr = (void *)mutex->addr;
   *destroyed = mutex->destroyed;
-  CopyTrace(mutex->stack->frames, trace, trace_size);
+  if (mutex->stack) CopyTrace(mutex->stack->frames, trace, trace_size);
   return 1;
 }
 
 SANITIZER_INTERFACE_ATTRIBUTE
 int __tsan_get_report_thread(void *report, uptr idx, int *tid, uptr *pid,
                              int *running, const char **name, int *parent_tid,
                              void **trace, uptr trace_size) {
   const ReportDesc *rep = (ReportDesc *)report;
   CHECK_LT(idx, rep->threads.Size());
   ReportThread *thread = rep->threads[idx];
   *tid = thread->id;
   *pid = thread->pid;
   *running = thread->running;
   *name = thread->name;
   *parent_tid = thread->parent_tid;
-  CopyTrace(thread->stack->frames, trace, trace_size);
+  if (thread->stack) CopyTrace(thread->stack->frames, trace, trace_size);
   return 1;
 }
 
 SANITIZER_INTERFACE_ATTRIBUTE
 int __tsan_get_report_unique_tid(void *report, uptr idx, int *tid) {
   const ReportDesc *rep = (ReportDesc *)report;
   CHECK_LT(idx, rep->unique_tids.Size());
   *tid = rep->unique_tids[idx];
   return 1;
 }