FpDebug: Check result of ReadThreadState. Do not use invalid data (on windows this lead to nil deref crash)

git-svn-id: trunk@61891 -

components/fpdebug/fpdbgclasses.pp

@@ -1720,7 +1720,7 @@ begin
     exit;
 
   t := GetInstructionPointerRegisterValue;
-  if Process.HasInsertedBreakInstructionAtLocation(t - 1) then begin
+  if (t <> 0) and Process.HasInsertedBreakInstructionAtLocation(t - 1) then begin
   (* There is a chance, that the code jumped to this Addr, instead of executing the breakpoint.
      But if the next signal for this thread is a breakpoint at this address, then
      it must be handled (even if the breakpoint has been removed since)
@@ -1760,14 +1760,17 @@ begin
   t := GetInstructionPointerRegisterValue;
   Result := ( (FPausedAtRemovedBreakPointState = rbFound) and
               (FPausedAtRemovedBreakPointAddress = t) ) or
-            Process.HasInsertedBreakInstructionAtLocation(t - 1);
+            ( (t <> 0) and Process.HasInsertedBreakInstructionAtLocation(t - 1) );
 debugln(['####### CHECK ',result, ' for id ', ID, ' stored ', FPausedAtRemovedBreakPointState=rbFound, ' ',FPausedAtRemovedBreakPointAddress=t, ' ',dbghex(t), ' ', dbghex(FPausedAtRemovedBreakPointAddress)]);
 end;
 
 procedure TDbgThread.CheckAndResetInstructionPointerAfterBreakpoint;
+var
+  t: TDBGPtr;
 begin
   // todo: check that the breakpoint is NOT in the temp removed list
-  if HasInsertedBreakInstructionAtLocation(GetInstructionPointerRegisterValue - 1)
+  t := GetInstructionPointerRegisterValue;
+  if (t <> 0) and HasInsertedBreakInstructionAtLocation(t - 1)
   then begin
     FPausedAtRemovedBreakPointState := rbFound;
     ResetInstructionPointerAfterBreakpoint;

components/fpdebug/fpdbglinuxclasses.pas

@@ -510,7 +510,7 @@ begin
 
   else
   if wstopsig(AWaitedStatus) = SIGTRAP then begin
-    ReadThreadState;
+    if ReadThreadState then
       CheckAndResetInstructionPointerAfterBreakpoint;
     Result := True;
     // TODO: main loop should search all threads for breakpoints
@@ -541,7 +541,8 @@ end;
 
 function TDbgLinuxThread.ResetInstructionPointerAfterBreakpoint: boolean;
 begin
-  ReadThreadState;
+  if not ReadThreadState then
+    exit(False);
   result := true;
   if FDidResetInstructionPointer then
     exit;
@@ -653,7 +654,8 @@ end;
 
 procedure TDbgLinuxThread.LoadRegisterValues;
 begin
-  ReadThreadState;
+  if not ReadThreadState then
+    exit;
   if Process.Mode=dm32 then
   begin
     FRegisterValueList.DbgRegisterAutoCreate['eax'].SetValue(FUserRegs.regs32[eax], IntToStr(FUserRegs.regs32[eax]),4,0);
@@ -706,7 +708,9 @@ end;
 
 function TDbgLinuxThread.GetInstructionPointerRegisterValue: TDbgPtr;
 begin
-  ReadThreadState;
+  Result := 0;
+  if not ReadThreadState then
+    exit;
   if Process.Mode=dm32 then
     result := FUserRegs.regs32[eip]
   else
@@ -715,7 +719,9 @@ end;
 
 function TDbgLinuxThread.GetStackBasePointerRegisterValue: TDbgPtr;
 begin
-  ReadThreadState;
+  Result := 0;
+  if not ReadThreadState then
+    exit;
   if Process.Mode=dm32 then
     result := FUserRegs.regs32[ebp]
   else
@@ -724,7 +730,9 @@ end;
 
 function TDbgLinuxThread.GetStackPointerRegisterValue: TDbgPtr;
 begin
-  ReadThreadState;
+  Result := 0;
+  if not ReadThreadState then
+    exit;
   if Process.Mode=dm32 then
     result := FUserRegs.regs32[UESP]
   else

components/fpdebug/fpdbgwinclasses.pas

@@ -1183,7 +1183,8 @@ end;
 procedure TDbgWinThread.LoadRegisterValues;
 begin
   if FCurrentContext = nil then
-    ReadThreadState;
+    if not ReadThreadState then
+      exit;
   {$ifdef cpui386}
   with FCurrentContext^.def do
   begin
@@ -1364,7 +1365,8 @@ end;
 procedure TDbgWinThread.SetSingleStep;
 begin
   if FCurrentContext = nil then
-    ReadThreadState;
+    if not ReadThreadState then
+      exit;
   {$ifdef cpux86_64}
   if (TDbgWinProcess(Process).FBitness = b32) then
     FCurrentContext^.WOW.EFlags := FCurrentContext^.WOW.EFlags or FLAG_TRACE_BIT // TODO WOW_FLAG....
@@ -1404,9 +1406,10 @@ function TDbgWinThread.AddWatchpoint(AnAddr: TDBGPtr): integer;
   end;
 
 begin
-  if FCurrentContext = nil then
-    ReadThreadState;
   result := -1;
+  if FCurrentContext = nil then
+    if not ReadThreadState then
+      exit;
   {$ifdef cpux86_64}
   if (TDbgWinProcess(Process).FBitness = b32) then begin
     with FCurrentContext^.WOW do
@@ -1475,8 +1478,10 @@ function TDbgWinThread.RemoveWatchpoint(AnId: integer): boolean;
   end;
 
 begin
+  Result := False;
   if FCurrentContext = nil then
-    ReadThreadState;
+    if not ReadThreadState then
+      exit;
   {$ifdef cpux86_64}
   if (TDbgWinProcess(Process).FBitness = b32) then begin
     with FCurrentContext^.WOW do
@@ -1551,7 +1556,8 @@ begin
     exit;
 
   if FCurrentContext = nil then
-    ReadThreadState;
+    if not ReadThreadState then
+      exit;
 
   {$ifdef cpui386}
   Dec(Context^.def.Eip);
@@ -1587,8 +1593,10 @@ end;
 
 function TDbgWinThread.GetInstructionPointerRegisterValue: TDbgPtr;
 begin
+  Result := 0;
   if FCurrentContext = nil then
-    ReadThreadState;
+    if not ReadThreadState then
+      exit;
 {$ifdef cpui386}
   Result := FCurrentContext^.def.Eip;
 {$else}
@@ -1601,8 +1609,10 @@ end;
 
 function TDbgWinThread.GetStackBasePointerRegisterValue: TDbgPtr;
 begin
+  Result := 0;
   if FCurrentContext = nil then
-    ReadThreadState;
+    if not ReadThreadState then
+      exit;
 {$ifdef cpui386}
   Result := FCurrentContext^.def.Ebp;
 {$else}
@@ -1615,8 +1625,10 @@ end;
 
 function TDbgWinThread.GetStackPointerRegisterValue: TDbgPtr;
 begin
+  Result := 0;
   if FCurrentContext = nil then
-    ReadThreadState;
+    if not ReadThreadState then
+      exit;
 {$ifdef cpui386}
   Result := FCurrentContext^.def.Esp;
 {$else}