[boost] [Boost-bugs] [ boost-Bugs-989168 ] intrusive_ptr may cause dungling ptr access

From: SourceForge.net (noreply_at_[hidden])
Date: 2004-07-11 22:04:51

Bugs item #989168, was opened at 2004-07-11 20:04
Message generated for change (Tracker Item Submitted) made by Item Submitter
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=107586&aid=989168&group_id=7586

Category: smart_ptr
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Peter Dimov (pdimov)
Summary: intrusive_ptr may cause dungling ptr access

Initial Comment:
I think intrusive_ptr may cause dungling ptr access in 
multithreaded environment.

Currently, it's constructor is:

    intrusive_ptr(T * p, bool add_ref = true)
    : p_(p)  /* the object may be deleted by other 
thread 
                because this thread does not increment 
reference counter yet. */
    {
        if(p_ != 0 && add_ref)
            intrusive_ptr_add_ref(p_); /* this may occur 
dungling ptr operation. */
    }

We can avoid this problem by "addref-before-use" policy.

    intrusive_ptr(T * p, bool add_ref = true)
    {
        if(p != 0 && add_ref)
            intrusive_ptr_add_ref(p_); /* other thread 
never delete the object */
        p_ = p;
    }

----------------------------------------------------------------------

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https://sourceforge.net/tracker/?func=detail&atid=107586&aid=989168&group_id=7586

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