Board index » cppbuilder » CodeGuard Access overrun

2006-07-01 02:38:24 AM
cppbuilder7
After doing a Version Query, I want to scan the data into 4 separate chunks
as follows:
if (VerQueryValue(aboutVerInfoBuffer, aboutVerBaseString.c_str(), &result,
&resultLen))
{
sscanf((char*)result, "%u.%u.%u.%u", &maj, &min, &rev, &bld);
}
where maj, min, rev, and bld are all unsigned ints and result is declared as
LPVOID.
At sscanf(), CodeGuard is giving me an Access overrun from an 'Attempt to
access 4 byte(s) at 0x0012F9F0, that is at offset 8 in local block
0x0012F9E8(=[ebp-0xA4] @Program1.exe:0x01:056A38) which is only 8 bytes
long.'
How can I fix this problem so that the access overrun will go away?
 

If it helps, VerQueryValue returns "1.0.5.8" to LPVOID result.
 

"poojo hackma" <poojo.com/mail>wrote in message
null-terminated. You need to use the resultLen value to know how long the
string actually, and then make a copy of the data when calling sscanf(), ie:
if( VerQueryValue(aboutVerInfoBuffer, aboutVerBaseString.c_str(),
&result, &resultLen) )
{
sscanf(AnsiString((char*)result, resultLen).c_str(), "%u.%u.%u.%u",
&maj, &min, &rev, &bld);
}
Exactly my point. The returned pointer was not null-terminated, so sscanf()
tried to access memory that was outside of the character data.
Gambit
 

{smallsort}

Thanks Gambit.
Now it looks like there is another CodeGuard error.
Values maj, min, rev, and bld are passed as follows:
int GetFileVersion(unsigned int &maj,
unsigned int &min,
unsigned int &rev,
unsigned int &bld)
{
unsigned int dummy[4];
<snip>
if (VerQueryValue(aboutVerInfoBuffer,
aboutVerBaseString.c_str(),
&result, &resultLen))
{
sscanf(AnsiString((char*)result, resultLen).c_str(),
"%u.%u.%u.%u",
&dummy[0], &dummy[1], &dummy[2], &dummy[3]);
maj = dummy[0];
min = dummy[1];
rev = dummy[2];
bld = dummy[3]; // <- CodeGuard: Attempt to access 2
// bytes that is offset 8 which is
// only 8 bytes long.
}
<snip>
}
Now CodeGuard does not like me assigning a value to bld.
Is there another key step I have overlooked?
 

"poojo hackma" <poojo.com/mail>wrote in message
earlier. They are all references, so they will always point to valid
variables. You are not gaining anything at all by using a separate array.
Something else has to be happening. Either CodeGuard is reporting the wrong
code line to begin with, or you have another dummy or bld variable somewhere
that is being accessed instead of the ones you have shown here.
Gambit
 

change it back after this gets fixed.
included all the info, but I could be mistaken.
//---------------------------------------------------------------------------
int TMainForm::GetFileVersion(INT_16U &maj, INT_16U &min,
INT_16U &rev, INT_16U &bld)
{
DWORD unused;
DWORD verSize;
LPVOID result;
char* ptr;
char* aboutVerInfoBuffer;
int i;
int iRet = 0;
unsigned int len;
unsigned int resultLen;
AnsiString aboutVerBaseString;
// First, get how big the VersionInfo buffer needs to be
// ParamStr(0) holds the complete path to the application
verSize = GetFileVersionInfoSize(ParamStr(0).c_str(), &unused);
if (verSize>0)
{
try
{
aboutVerInfoBuffer = new char[verSize + 1];
// Now, get the sort-of handle we'll use in further VerQueryValue
calls
if
(GetFileVersionInfo(ParamStr(0).c_str(),0,verSize,aboutVerInfoBuffer))
{ // Extract the language/translation information...
if (VerQueryValue(aboutVerInfoBuffer,
TEXT("\\VarFileInfo\\Translation"), &(void*)ptr, &len))
{ // ptr comes back as a ptr to two (16-bit) words containing the
two halves of
// the translation number required for StringFileInfo
aboutVerBaseString = AnsiString( "\\StringFileInfo\\")+
IntToHex(((WORD*)ptr)[0],4) +
IntToHex(((WORD*)ptr)[1],4) + "\\FileVersion";
if (VerQueryValue(aboutVerInfoBuffer, aboutVerBaseString.c_str(),
&result, &resultLen))
{
sscanf(AnsiString((char*)result, resultLen).c_str(),
"%u.%u.%u.%u", &maj, &min, &rev, &bld);
iRet = 1;
}
}
}
else {
AnsiString aErr = "GetFileVersion failed:\n" +
SysErrorMessage(::GetLastError());
MessageBox(Handle, aErr.c_str(), "GetFileVersion Error", MB_OK |
MB_ICONERROR);
}
}
__finally {
delete[] aboutVerInfoBuffer;
}
}
return iRet;
}
 

"poojo hackma" <poojo.com/mail>wrote in message
each locale. It is easier to pull them from the root '\' block instead of
from the 'Translation' table. You also don't need to use sscanf() anymore
if you do that. For example:
int TMainForm::GetFileVersion(INT_16U &maj, INT_16U &min, INT_16U &rev,
INT_16U &bld)
{
AnsiString strFile = ParamStr(0);
DWORD unused;
int iRet = 0;
DWORD verSize = GetFileVersionInfoSize(strFile.c_str(), &unused);
if( verSize>0 )
{
LPVOID verInfoBuffer = LocalAlloc(LMEM_FIXED, verSize);
if( verInfoBuffer )
{
if( GetFileVersionInfo(strFile.c_str(), unused, verSize,
verInfoBuffer) )
{
VS_FIXEDFILEINFO *verInfo = NULL;
UINT verLen;
if( VerQueryValue(verInfoBuffer, TEXT("\\"),
(void**)&verInfo, &verLen) )
{
maj = HIWORD(verInfo->dwFileVersionMS);
min = LOWORD(verInfo->dwFileVersionMS);
rev = HIWORD(verInfo->dwFileVersionLS);
bld = LOWORD(verInfo->dwFileVersionLS);
iRet = 1;
}
else
{
AnsiString aErr = "VerQueryValue failed:\n" +
SysErrorMessage(GetLastError());
MessageBox(Handle, aErr.c_str(), "GetFileVersion
Error", MB_OK | MB_ICONERROR);
}
}
else
{
AnsiString aErr = "GetFileVersionInfo failed:\n" +
SysErrorMessage(GetLastError());
MessageBox(Handle, aErr.c_str(), "GetFileVersion Error",
MB_OK | MB_ICONERROR);
}
LocalFree(verInfoBuffer);
}
else
{
AnsiString aErr = "LocalAlloc failed:\n" +
SysErrorMessage(GetLastError());
MessageBox(Handle, aErr.c_str(), "GetFileVersion Error",
MB_OK | MB_ICONERROR);
}
}
return iRet;
}
Gambit
 

Just some problems I notice in your code - I'm afraid the list is not
exhaustive.
"poojo hackma" <poojo.com/mail>writes:
definition list is longer that an entire function should be in total
IMHO.
Also, prefer to define variables where you need them and where you
know how to initialize them.
__finally scaffolding.
address most likely does not what you expect it does.
2) sscanf() returns a value that you should inspect before reading
maj, min, rev and bld.
E.g.:
std::string const tmp(static_cast<char *>(result),resultLen);
if (sscanf(tmp.c_str(),"%u.%u.%u.%u", &maj, &min, &rev, &bld)==4)
; // use maj, min, rev, bld
else
; // deal with conversion failure
 

"Thomas Maeder [TeamB]" < XXXX@XXXXX.COM >wrote in message
call to sscanf() is complete.
Gambit