[zeromq-dev] Bad Pointer Exception with ZMQ 2.2.X

[Martin Hurton]

Is this reproducible?

- Martin

On Fri, Jul 20, 2012 at 12:31 AM, Viviano, Aaron
<Aaron.Viviano at quadtechworld.com> wrote:
> Hello ZeroMQ Devs,
>
> I’m currently running into an issue with ZMQ, using CLRZMQ (Win7, VS2010),
> where it is crashing in the encoder::get_data function at this line:
>
>
>
> memcpy (buffer + pos, write_pos, to_copy);
>
>
>
> The variable write_pos would equal 0xfeeefeee, which according to what I’ve
> researched, means that the pointer was last touched by Window’s HeapFree
> function [1]. Looking into the code I’ve found that this variable is set
> with the address from the msg_content_t::*data variable. This is then
> cleaned up in zmq_msg_close:
>
>
>
> if (content->ffn)
>
>     content->ffn (content->data, content->hint);
>
> free (content);
>
>
>
> I’ve attempted to add a function call in zmq::encoder_t::message_ready to a
> function called zmq_CheckForFreedData to try and fix the problem.
>
>
>
> bool zmq_CheckForFreedData(zmq_msg_t *msg_)
>
> {
>
>        if (msg_->content == (zmq::msg_content_t*) ZMQ_VSM)
>
>         return false;
>
>        if (msg_->content == (zmq::msg_content_t*) ZMQ_DELIMITER)
>
>         return false;
>
>
>
>        if(((zmq::msg_content_t*) msg_->content)->data == (void *)0xfeeefeee)
>
>        {
>
>               return true;
>
>        }
>
>        return false;
>
> }
>
>
>
> …
>
> if (!source || !source->read (&in_progress))
>
> {
>
>        zmq_msg_init (&in_progress);
>
>        return false;
>
> }
>
> else if(zmq_CheckForFreedData(&in_progress))
>
> {
>
>        zmq_msg_init (&in_progress);
>
>        return false;
>
> }
>
> …
>
>
>
> While this prevents the crash I’m now seeing my  program lock up. At the
> moment I don’t have a simple test program for you, however, until I have the
> chance to put one together, what would be the best place to start looking
> for why this error is happening in the code?
>
>
>
> Thank you,
>
> Aaron
>
>
>
> 1.
> http://stackoverflow.com/questions/127386/in-visual-studio-c-what-are-the-memory-allocation-representations
>
>
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