Bugs item #3001207, was opened at 2010-05-13 17:56
Message generated for change (Tracker Item Submitted) made by nobody
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: PoDoFo dereferencing null pointer when out-of-memory
Initial Comment:
Hello,
I believe I have found a bug within PoDoFo when the system is out of memory
during a Stream Write.
Here is what I see:
PdfMemoryOutputStream::Write()
{
...
m_pBuffer = static_cast<char*>(podofo_realloc( m_pBuffer, m_lSize ));
if( !m_pBuffer )
{
PODOFO_RAISE_ERROR( ePdfError_OutOfMemory );
}
...
}
throws a ePdfError_OutOfMemory exception, unwinding us to:
void PdfFlateFilter::EncodeBlockInternal( )
{
...
try {
if( nWrittenData > 0 )
{
GetStream()->Write( reinterpret_cast<char*>(m_buffer),
nWrittenData );
}
} catch( PdfError & e ) {
// clean up after any output stream errors
FailEncodeDecode();
e.AddToCallstack( __FILE__, __LINE__ );
throw e;
}
...
}
The catch statement here handles the exception, calling FailEncodeDecode() and
then re-throwing the exception.
Note the body of FailEncodeDecode() :
void PdfFilter::FailEncodeDecode()
{
m_pOutputStream->Close();
m_pOutputStream = NULL;
}
now, since EncodeBlockInternal() re-throws we unwind to its caller:
void PdfFilter::EncodeBlock( )
{
PODOFO_RAISE_LOGIC_IF( !m_pOutputStream, "EncodeBlock() without
BeginEncode() or on failed filter" );
try {
EncodeBlockImpl(pBuffer, lLen);
} catch( const PdfError & e ) {
// Clean up and close stream
this->FailEncodeDecode();
throw e;
}
}
Which is where the problem occurs, FailEncodeDecode() is called a second time
and attempts to call Close() on the (now null) m_pOutputStream pointer.
I suppose a simple check in FailEncodeDecode() on the pointer would fix this ie:
void PdfFilter::FailEncodeDecode()
{
if (m_pOutputStream) {
m_pOutputStream->Close();
m_pOutputStream = NULL;
}
}
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