如何使用 GFlags 设置Enable heap tagging by DLL并从中受益？
!heap -t我知道如何激活进程的设置，但在 WinDbg的输出中没有找到有用的信息。我期待一些这样的输出：
0:000> !heap -t
Index Address Allocated by
1: 005c0000 MyDll.dll
2: 006b0000 AnotherDll.dll
这样我就可以确定哪个堆是由哪个 DLL 创建的，然后例如确定内存泄漏的来源。
这是对“由 DLL 进行堆标记”一词的误解，还是我需要更多命令才能获得所需的结果？
到目前为止我的研究：
.hh !heap，但也没有详细解释。标签仅用于!heap -b又是一个很晚的答案
you need to create a tag在您的代码中首先从 HeapTagging 中受益。
据我所知（最高到xp-sp3）有no Documented APIS to Create a tag
（从那以后我没有搞砸堆，所以我不知道 os > vista 中的最新 api 对堆管理器进行了重写，所以^^^features^^^我在下面发布的许多内容可能已经被纠正或改进或删除了错误）
在 xp-sp3 中，您可以使用 undocumentedRtlCreateTagHeap创建一个新Process Heap标签Private Heap
创建 tha 标签后，您需要设置全局标志 8000 | 800
htg - Enable heap tagging
htd - Enable heap tagging by DLL
和theoratically all allocs and frees must get tagged。
但practically only allocations > 512 kB gets tagged在 xp-sp3 中有这些基本步骤
它要么是一个错误，要么是一个将标记限制为分配的功能，
HeapAlloc goes through ZwAllocateVirtualMemory如果在 32 位进程中分配 > 512 kB，则释放 > 512 kBrefer HeapCreate / HeapAlloc Documentation in msdn
并且作为一个debuging aid你可以patch ntdll.dll为the fly to enable tagging。all Allocations and frees
下面是一个示例代码，演示了标记以及如何在 windbg 中查看所有内容
编译使用cl /Zi /analyze /W4 <src> /link /RELEASE
使用 windbg 执行应用程序并使用!heap * -t命令查看标记
#include <windows.h>
#include <stdio.h>
//heaptags are kinda broken or they are intentionally
//given only to allocations > 512 kb // allocation > 512 kb
//go through VirtualAlloc Route for Heap created with maxsize
//set to 0 uncomment ALLOCSIZE 0xfdfd2 and recompile to watch
// tagging increase by 100% with ALLOCSIZE 0xfdfd1 only 50 allocs
// and frees that are > 512 kB will be tagged these magic numbers
// are related to comment in HeapCreate Documentation that state
// slightly less than 512 kB will be allocated for 32 bit process
// tagging can be dramatically increased by patching ntdll when
// stopped on system breakpoint patch 7c94b8a4 (xpsp3 ntdll.dll)
// use the below command in windbg for finding the offset of pattern
// command must be in single line no line breaks
// .foreach /pS 4 /ps 4 ( place { !grep -i -e call -c
// "# call*RtlpUpdateTagEntry 7c900000 l?20000" } ) { ub place }
// the instruction we are searching to patch is
//7c94b8a1 81e3ff0fffff and ebx,0FFFF0FFFh
// patch 0f to 00 at system breakpoint with eb 7c94b8a1+3 00
#define BUFFERSIZE 100
#define ALLOCSIZE 0xfdfd1
//#define ALLOCSIZE 0xfdfd2
typedef int ( __stdcall *g_RtlCreateTagHeap) (
HANDLE hHeap ,
void * unknown,
wchar_t * BaseString,
wchar_t * TagString
);
void HeapTagwithHeapAllocPrivate()
{
PCHAR pch[BUFFERSIZE] = {};
HANDLE hHeap = 0;
ULONG tag1 = 0;
ULONG tag2 = 0;
ULONG tag3 = 0;
ULONG tag4 = 0;
ULONG tag5 = 0;
g_RtlCreateTagHeap RtlCreateTagHeap = 0;
HMODULE hMod = LoadLibrary("ntdll.dll");
if(hMod)
{
RtlCreateTagHeap = (g_RtlCreateTagHeap)
GetProcAddress( hMod,"RtlCreateTagHeap");
}
if (hHeap == 0)
{
hHeap = HeapCreate(0,0,0);
if (RtlCreateTagHeap != NULL)
{
tag1 = RtlCreateTagHeap (hHeap,0,L"HeapTag!",L"MyTag1");
tag2 = RtlCreateTagHeap (hHeap,0,L"HeapTag!",L"MyTag2");
tag3 = RtlCreateTagHeap (hHeap,0,L"HeapTag!",L"MyTag3");
tag4 = RtlCreateTagHeap (hHeap,0,L"HeapTag!",L"MyTag4");
}
}
HANDLE DefHeap = GetProcessHeap();
if ( (RtlCreateTagHeap != NULL) && (DefHeap != NULL ))
{
tag5 = RtlCreateTagHeap (DefHeap,0,L"HeapTag!",L"MyTag5");
for ( int i = 0; i < BUFFERSIZE ; i++ )
{
pch[i]= (PCHAR) HeapAlloc( DefHeap,HEAP_ZERO_MEMORY| tag5, 1 );
HeapFree(DefHeap,NULL,pch[i]);
}
}
if(hHeap)
{
for ( int i = 0; i < BUFFERSIZE ; i++ )
{
pch[i]= (PCHAR) HeapAlloc( hHeap,HEAP_ZERO_MEMORY| tag1, 1 );
//lets leak all allocs patch ntdll to see the tagging details
//HeapFree(hHeap,NULL,pch[i]);
}
for ( int i = 0; i < BUFFERSIZE ; i++ )
{
pch[i]= (PCHAR) HeapAlloc( hHeap,HEAP_ZERO_MEMORY| tag2, 100 );
// lets leak 40% allocs patch ntdll to see the tagging details
if(i >= 40)
HeapFree(hHeap,NULL,pch[i]);
}
// slightly less than 512 kb no tagging
for ( int i = 0; i < BUFFERSIZE / 2 ; i++ )
{
pch[i]= (PCHAR) HeapAlloc(
hHeap,HEAP_ZERO_MEMORY| tag3, ALLOCSIZE / 2 );
}
// > 512 kb default tagging
for ( int i = BUFFERSIZE / 2; i < BUFFERSIZE ; i++ )
{
pch[i]= (PCHAR) HeapAlloc(
hHeap,HEAP_ZERO_MEMORY | tag4 ,ALLOCSIZE );
}
for (int i =0 ; i < BUFFERSIZE ; i++)
{
HeapFree(hHeap,NULL,pch[i]);
}
}
}
void _cdecl main()
{
HeapTagwithHeapAllocPrivate();
}
与windbg一起运行的编译exe如下
默认执行和检查
**只有 50 个标签可见，所有标签均 > 512 kB
cdb -c "g;!heap * -t;q" newheaptag.exe | grep 标签**
heaptag:\>cdb -c "g;!heap * -t;q" newheaptag.exe | grep Tag
Tag Name Allocs Frees Diff Allocated
Tag Name Allocs Frees Diff Allocated
Tag Name Allocs Frees Diff Allocated
0004: HeapTag!MyTag4 50 50 0 0
在系统断点上修补 ntdll 应该使所有标签可见
eb = 写入字节 补丁并在退出检查堆时运行带有标签的 exe cdb -c "eb 7c94b8a1+3 00;g;!heap * -t;q" newheaptag.exe | grep 标签
heaptag:\>cdb -c "eb 7c94b8a1+3 00;g;!heap * -t;q" newheaptag.exe | grep Tag
Tag Name Allocs Frees Diff Allocated
0012: HeapTag!MyTag5 100 100 0 0 <-our tag in process heap
Tag Name Allocs Frees Diff Allocated
Tag Name Allocs Frees Diff Allocated
0001: HeapTag!MyTag1 100 0 100 3200 <--- leak all
0002: HeapTag!MyTag2 100 60 40 5120 <--- leak 40 %
0003: HeapTag!MyTag3 50 50 0 0 <--- clean < 512 kB
0004: HeapTag!MyTag4 50 50 0 0 <----clean > 512 kB