[Vm-dev] [BUG] CogVM crash on Windows

[Levente Uzonyi]

Hi,


evaluating [Display newDepth: x] where the value of x is 1, 4, 8 or 16 
crashes the VM. No crash dump is written. If x is 2, -1, -2 or -4, then 
the image informs me that the depth is not available on the system. If x 
is -8 or -16 then the code works. For the x=16 case gdb shows the 
following:

Program received signal SIGSEGV, Segmentation fault.
reverse_image_words (dst=0x1450eca4, src=0x1450eca4, depth=0, width=1272,
     rect=0x561e60) at ../platforms/win32/vm/sqWin32Window.c:1875
1875            unsigned int value = *srcPixPtr++;
(gdb) where
#0  reverse_image_words (dst=0x1450eca4, src=0x1450eca4, depth=0, width=1272,
     rect=0x561e60) at ../platforms/win32/vm/sqWin32Window.c:1875
#1  0x0043f61a in ioShowDisplay (dispBits=340847780, width=1272, height=745,
     depth=16, affectedL=0, affectedR=1000, affectedT=0, affectedB=0)
     at ../platforms/win32/vm/sqWin32Window.c:2324
#2  0x00403270 in displayBitsOfLeftTopRightBottom (aForm=-719257650, l=0,
     t=0, r=1272, b=745) at ../src/vm/gcc3x-cointerp.c:13701
#3  0x00405ff9 in fullDisplayUpdate () at ../src/vm/gcc3x-cointerp.c:16777
#4  0x0044093a in MainWndProcW (hwnd=0xf05f6, message=15, wParam=0, lParam=0)
     at ../platforms/win32/vm/sqWin32Window.c:447
#5  0x75fef8d2 in USER32!GetMessageW ()
    from /cygdrive/c/Windows/system32/user32.dll
#6  0x75fef794 in USER32!GetWindowLongW ()
    from /cygdrive/c/Windows/system32/user32.dll
#7  0x004403dc in sqLaunchDrop ()
     at ../platforms/win32/vm/sqWin32Window.c:2773
#8  0x75ff0817 in USER32!ReleaseDC ()
    from /cygdrive/c/Windows/system32/user32.dll
#9  0x75ff0a65 in USER32!GetWindowThreadProcessId ()
    from /cygdrive/c/Windows/system32/user32.dll
#10 0x776a99ce in ntdll!LdrEnumResources ()
    from /cygdrive/c/Windows/system32/ntdll.dll
#11 0x00ace008 in ?? ()
#12 0x00000018 in ?? ()
---Type <return> to continue, or q <return> to quit---
#13 0x00ace058 in ?? ()
#14 0x776a9980 in ntdll!LdrDisableThreadCalloutsForDll ()
    from /cygdrive/c/Windows/system32/ntdll.dll
#15 0x0204c1d8 in ?? ()
#16 0x0000000f in ?? ()
#17 0x00000000 in ?? ()
(gdb) info registers
eax            0xd520ffce       -719257650
ecx            0x3      3
edx            0x0      0
ebx            0x1f4    500
esp            0xacd5b4 0xacd5b4
ebp            0x0      0x0
esi            0x1511a000       353476608
edi            0x1511a000       353476608
eip            0x43ed0c 0x43ed0c <reverse_image_words+353>
eflags         0x10216  [ PF AF IF RF ]
cs             0x1b     27
ss             0x23     35
ds             0x23     35
es             0x23     35
fs             0x3b     59
gs             0x0      0

It may be a compiler bug, because the 4.0.2 SqueakVM doesn't have this 
issue. It's a bit suspicious that depth is 0 here:
#0  reverse_image_words (dst=0x1450eca4, src=0x1450eca4, depth=0, width=1272,
     rect=0x561e60) at ../platforms/win32/vm/sqWin32Window.c:1875
but the value of depth is known at compilation time (16), so it may be 
some compiler "magic".
Here are the values of the variables in the method:
(gdb) p dst
$2 = (unsigned int *) 0x1450eca4
(gdb) p src
$3 = (unsigned int *) 0x1450eca4
(gdb) p depth
$4 = 0
(gdb) p width
$5 = 1272
(gdb) p rect
$6 = (RECT *) 0x561e60
(gdb) p rect->left
$7 = 0
(gdb) p rect->right
$8 = 1000
(gdb) p rect->top
$9 = 0
(gdb) p rect->bottom
$10 = 745
(gdb) p pitch
$11 = 353476608
(gdb) p first
$12 = 3
(gdb) p last
No symbol "last" in current context.
(gdb) p nWords
$13 = 500
(gdb) p delta
$14 = 0
(gdb) p yy
$15 = 0
(gdb) p srcPixPtr
$16 = (DWORD *) 0x1511a000
(gdb) p dstPixPtr
$17 = (DWORD *) 0x1511a000
(gdb) p i
$18 = -719257650
(gdb) p value
$19 = 0


Cheers,
Levente