From timurrrr@google.com on August 26, 2011 07:24:52

Leaks on a similar program:

#include <windows.h>
#include <dbghelp.h>
#pragma comment(lib, "dbghelp.lib")

#include <stdio.h>

int main() {
STACKFRAME64 stack_frame;
memset(&stack_frame, 0, sizeof(stack_frame));
CONTEXT cxt;
memset(&cxt, 0, sizeof(cxt));
stack_frame.AddrPC.Mode = AddrModeFlat;
stack_frame.AddrFrame.Mode = AddrModeFlat;
stack_frame.AddrStack.Mode = AddrModeFlat;
while (StackWalk64(IMAGE_FILE_MACHINE_I386, GetCurrentProcess(),
GetCurrentThread(), &stack_frame,
&cxt, NULL,
&SymFunctionTableAccess64, &SymGetModuleBase64, NULL)) {
printf("Frame: 0x%08X\n", stack_frame.AddrPC.Offset);
}
}

Error #1: LEAK 896 direct bytes 0x002307e0-0x00230b60 + 0 indirect bytes
0x73f8d92e <dbghelp.dll+0xd92e> dbghelp.dll!SymGetModuleInfoW64
0x73f94fce <dbghelp.dll+0x14fce> dbghelp.dll!SymFromAddrW
0x73f964c8 <dbghelp.dll+0x164c8> dbghelp.dll!StackWalk64
0x004010a5 <test.exe+0x10a5> test.exe!main
c:\sandbox\stackwalk\test.cpp:18

From bruen...@google.com on August 26, 2011 07:30:50

don't you need to call SymInitialize and SymCleanup? does the leak go away if you do that?

From timurrrr@google.com on August 26, 2011 07:35:33

MSDN says nothing about it on the StackWalk64 page.

The leak is still there if I call these guys.

From bruen...@google.com on August 26, 2011 07:42:29

The MSDN page is terrible: it doesn't do a good job of telling you how to initialize the frame (your sample does it incorrectly: my understanding is that you need to fill in the values of PC, Frame, and Stack). But for the function pointers it says you could use the dbghelp ones, which to me implies only if you've set up dbghelp already. I've tried using StackWalk64 and it did not work well for me unless I loaded the module symbols up front w/ SymIninitialize(,,TRUE). Xref issue #563 .

From timurrrr@google.com on August 26, 2011 07:47:46

With (,,TRUE) it gives 400+ uninits like this:
Error #X: UNINITIALIZED READ
...
0x73f997c8 <dbghelp.dll+0x197c8> dbghelp.dll!StackWalk64
0x73fb9646 <dbghelp.dll+0x39646> dbghelp.dll!FindExecutableImage
0x73fb98ea <dbghelp.dll+0x398ea> dbghelp.dll!FindExecutableImage
0x73f98563 <dbghelp.dll+0x18563> dbghelp.dll!StackWalk64
0x73fb58d0 <dbghelp.dll+0x358d0> dbghelp.dll!SymInitialize
0x00416a74 <test.exe+0x16a74> test.exe!main
c:\sandbox\stackwalk\test.cpp:8

and the leak is still there! :)

From bruen...@google.com on August 26, 2011 07:50:07

(in general) can you include the "Note: instruction:" which can provide a hint as to whether bit granularity is the issue

From timurrrr@google.com on August 26, 2011 07:59:41

Sure,
$ grep "Note: ins" results.txt | sort | uniq -c | sort
2 Note: instruction: cmp %eax $0x00000003
2 Note: instruction: test %esi %esi
2 Note: instruction: test 0xfffffffc(%ebp) $0x00000100
2 Note: instruction: test 0xfffffffc(%ebp) $0x20
8 Note: instruction: test %bl $0x10
12 Note: instruction: cmp %edi $0x00000001
14 Note: instruction: test %eax $0x00000400
14 Note: instruction: test 0x04(%esi) $0x0f
50 Note: instruction: test %ecx %ecx
308 Note: instruction: test %eax %eax