https://bugs.documentfoundation.org/show_bug.cgi?id=98930
Bug ID: 98930
Summary: Integer values passed to a C++ function, appear to
corrupt stack
Product: LibreOffice
Version: 5.0.4.2 release
Hardware: All
OS: All
Status: UNCONFIRMED
Severity: normal
Priority: medium
Component: BASIC
Assignee: [email protected]
Reporter: [email protected]
Created attachment 123896
--> https://bugs.documentfoundation.org/attachment.cgi?id=123896&action=edit
C++ project
May be related to: https://bugs.documentfoundation.org/show_bug.cgi?id=88953
I am using a macro to pass values to an existing third party C++ library that
does further processing. For bug-reporting purposes I made the sample as small
as I could.
Steps to reproduce:
1) Build the attached C++ project (the project file is VS2015), place the
resulting DLL in the DLL search path (for example: syswow64 or system32).
2) Create a LibreOffice macro with the following contents:
### START SAMPLE ###
REM ***** BASIC *****
Declare Function fnlotest Lib "lotest.dll" (integer, integer, integer,
integer) As Integer
Declare Function fnlotest2 Lib "lotest.dll" (String, String, String, String,
String) As Integer
declare sub MyMessageBeep Lib "user32.dll" Alias "MessageBeep" (Long)
Sub Main
MyMessageBeep(5000) ' Test
Dim szBuffer as string
Dim ret as integer
szBuffer = Space(512)
ret = fnlotest(1,2,3,4) ' Expected result: 1+2+3+4 = 10, actual result: 3
fnlotest2(szBuffer, "foo", "bar", "hello", "world")
End Sub
### END SAMPLE ###
3) Run the sample and verify the return value of fnlotest(1,2,3,4). It should
add all numbers.
If you run the sample while having the C++ debugger attached, you will see that
the parameters that come through are: 1, 0, 2, 0 instead of 1,2,3,4. Explaining
why we get 3 as a result.
Interestingly, the second function with string values is fine.
The third-party DLL uses functions with a signature like:
foo(int, char*)
Because the stack appears to be corrupted after the first integer passed to a
function, we get an access violation when accessing the char *.
We tested with older versions, and the last working version is: 4.3.7.2
Currently we are running 5.0.4.2
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