version: Fix wrong length reported when selecting a block. (resend)

[Mark Jansen]

Hello,

VersionInfo32_QueryValue seeks the requested element in a resource,
and the check after that (which i patched) asks if this succeeded, and
if it succeeded if it is text.
Now there are some rare case where it succeeds, and where it is text
but the length is actually 0.
The data at this point should not matter, but because the check did
not take into account the length returned, and blindly fed the data to
WideCharToMultiByte (which uses some pointer trickery that in this
very specific case is wrong to calculate the length), the result is
VerQueryValueA telling you that it just found you x bytes of data,
where it should have reported 0. (x depending on the data encountered
at the current read position, usually 0 so usually it accidentally
gives the correct value back.

The 'dum' i introduced is purely to make sure the function doesnt trip
if someone gives it a NULL pointer.

regards,

On Fri, Feb 13, 2015 at 11:27 AM, Stefan Dösinger
<stefandoesinger at gmail.com> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
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> Am 2015-02-12 um 20:15 schrieb Mark Jansen:
>>          LPWSTR lpSubBlockW;
>> +        UINT dum = 0;
>> +        if (!puLen)
>> +            puLen = &dum;
>>
>>          len  = MultiByteToWideChar(CP_ACP, 0, lpSubBlock, -1, NULL, 0);
>>          lpSubBlockW = HeapAlloc(GetProcessHeap(), 0, len * sizeof(WCHAR));
>> @@ -965,7 +968,7 @@ BOOL WINAPI VerQueryValueA( LPCVOID pBlock, LPCSTR lpSubBlock,
>>
>>          HeapFree(GetProcessHeap(), 0, lpSubBlockW);
>>
>> -        if (ret && isText)
>> +        if (ret && isText && *puLen)
> I am afraid I have no idea what this patch is doing. I am not even sure
> I understand the original function properly :-( . VerQueryValueA seems
> like an A to W wrapper for VersionInfo32_QueryValue, but with the quirky
> behavior that it appends the ascii string after the unicode string.
>
> Can you elaborate a bit on what exactly goes wrong? What are the input
> values, and what does VersionInfo32_QueryValue return?
>
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