Re: EnterCriticalSection() is corrupting my heap

From:
"Oleg Starodumov" <com-dot-debuginfo-at-oleg>
Newsgroups:
microsoft.public.dotnet.languages.vc,microsoft.public.vc.debugger,microsoft.public.vc.language
Date:
Wed, 24 May 2006 16:52:42 +0300
Message-ID:
<O6h$9lzfGHA.5092@TK2MSFTNGP04.phx.gbl>

In my outside code:

{
    CAutoLock(&m_cs);

    // Some code
}

CAutoLock::CAutoLock(CRITICALSECTION *pCS)
{
    m_pCS = pCS; <= This assignement is not working correctly and after
assignment m_pCS points to some garbage memory location
    EnterCriticalSection(m_pCS);
}

So any idea what is wrong?


There can be a problem with the way the function is called (I mean the function
that instantiates CAutoLock object). It could be that it is called via a bad object
pointer, as a result "this" pointer passed to the function contains wrong value,
and so on. The next time you reproduce the problem, take a look at the value
of "this" passed to that function, and check if it's correct.

I mean something like this:

class CObj
{
  ...
  CRITICAL_SECTION m_cs;
  void YourFunc(); // instantiates CAutoLock and passes it &m_cs
}

CObj pObj; // not initialized, for example
pObj->YourFunc(); // when it is called, "this" pointer is bad, and thus pointers to
  // its data members will also be bad

Generic safety checks for heap corruptions with PageHeap would not harm too,
try to enable it as described here:
http://www.debuginfo.com/tips/userbpntdll.html

Oleg

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