UNINIT on calc in gdiplus.dll!DpRegion::FreeData: needs per-bit granularity

_From [bruen...@google.com](https://code.google.com/u/109494838902877177630/) on July 15, 2011 13:36:27_

happens on win7 calc with "scientific view"

Error `#3`: UNINITIALIZED READ: reading 0x02fb26e4-0x02fb26e5 1 byte(s)
0x7256a60d gdiplus.dll!DpRegion::FreeData
0x7257a7bc gdiplus.dll!GpGraphics::UpdateDrawBounds
0x7257ace8 gdiplus.dll!GpGraphics::ResetState
0x7257c284 gdiplus.dll!GpGraphics::GpGraphics
0x7257c96b gdiplus.dll!GpGraphics::GetFromGdiScreenDC
0x7257ccf0 gdiplus.dll!GpGraphics::GetFromHdc
0x725582e8 gdiplus.dll!GdipCreateFromHDC
0x00db82ae calc.exe!Gdiplus::Graphics::Graphics
0x00db836a calc.exe!DrawPNGImageForStatic
0x00db8331 calc.exe!CGlowButton::DrawButtonText
0x00dbdd56 calc.exe!CScientificKeypad::DrawItemText
0x00dbdd7f calc.exe!CScientificMode::SciDlgProc
0x7256a60d f6 46 04 04 test 0x04(%esi) $0x04

looks like it's reading an early (first non-vtable?) field in DpRegion:
gdiplus!DpRegion::FreeData:
7256a608 8bff mov edi,edi
7256a60a 56 push esi
7256a60b 8bf1 mov esi,ecx
7256a60d f6460404 test byte ptr [esi+0x4],0x4
0:000> dd @@(mc->esi)
02e526e0 67526431 00000001 ffc00000 ffc00000

bp gdiplus!DpRegion::DpRegion
there are 4: I did them all, and hit one:
0:000> dd ecx L4
02dd258c baadf00d baadf00d baadf00d baadf00d
0:000> ba r4 ecx+4
0:000> g
Breakpoint 4 hit
eax=02dd258c ebx=00000000 ecx=02dd258c edx=00000001 esi=02dd2588 edi=00000000
eip=725e9a01 esp=0022df64 ebp=0022df64 iopl=0 nv up ei ng nz na po nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00000286
gdiplus!DpRegion::DpRegion+0xb:
725e9a01 8b4804 mov ecx,[eax+0x4] ds:002b:02dd2590=baadf009
0:000> Uf 725e99f6
gdiplus!DpRegion::DpRegion:
725e99f6 8bff mov edi,edi
725e99f8 55 push ebp
725e99f9 8bec mov ebp,esp
725e99fb 8bc1 mov eax,ecx
725e99fd 836004fb and dword ptr [eax+0x4],0xfffffffb <== ~0x4
725e9a01 8b4804 mov ecx,[eax+0x4]
725e9a04 33d2 xor edx,edx
725e9a06 895018 mov [eax+0x18],edx
725e9a09 395508 cmp [ebp+0x8],edx
725e9a0c 7521 jnz gdiplus!DpRegion::DpRegion+0x39 (725e9a2f)

gdiplus!DpRegion::DpRegion+0x18:
725e9a0e 83e1fd and ecx,0xfffffffd
725e9a11 83c901 or ecx,0x1
725e9a14 894804 mov [eax+0x4],ecx
725e9a17 b90000c0ff mov ecx,0xffc00000
725e9a1c 894808 mov [eax+0x8],ecx
725e9a1f 89480c mov [eax+0xc],ecx
725e9a22 b900004000 mov ecx,0x400000
725e9a27 894810 mov [eax+0x10],ecx
725e9a2a 894814 mov [eax+0x14],ecx
725e9a2d eb15 jmp gdiplus!DpRegion::DpRegion+0x4e (725e9a44)

gdiplus!DpRegion::DpRegion+0x39:
725e9a2f 83e1fe and ecx,0xfffffffe
725e9a32 83c902 or ecx,0x2
725e9a35 894804 mov [eax+0x4],ecx
725e9a38 895008 mov [eax+0x8],edx
725e9a3b 89500c mov [eax+0xc],edx
725e9a3e 895010 mov [eax+0x10],edx
725e9a41 895014 mov [eax+0x14],edx

gdiplus!DpRegion::DpRegion+0x4e:
725e9a44 c70031645267 mov dword ptr [eax],0x67526431
725e9a4a 89501c mov [eax+0x1c],edx
725e9a4d 5d pop ebp
725e9a4e c20400 ret 0x4

so it's doing some bit games.
like issue #492 and issue #493 I suspect this would go away w/ per-bit granularity
so planning to suppress for now.

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=497_