Re: [dpdk-dev] [PATCH v2] ip_frag: fix double free of chained mbufs

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> -----Original Message-----
> From: Legacy, Allain [mailto:Allain.Legacy@windriver.com]
> Sent: Wednesday, April 11, 2018 12:28 PM
> To: Ananyev, Konstantin <konstantin.ananyev@intel.com>
> Cc: dev@dpdk.org; Peters, Matt (Wind River) <matt.peters@windriver.com>; stable@dpdk.org
> Subject: RE: [PATCH v2] ip_frag: fix double free of chained mbufs
> 
> > -----Original Message-----
> > From: Ananyev, Konstantin [mailto:konstantin.ananyev@intel.com]
> > Sent: Wednesday, April 11, 2018 7:02 AM
> <..>
> >
> >
> > I wonder why we have to NULL only first and cur entry?
> > We probably have to NULL each one in that case, right?
> 
> We have to do first and current entries at those locations because
> the code does not clear them properly.  All other entries are cleared by
> the following piece of code but it does not handle the two cases that I am
> addressing with my change.
> 
> 	/* this mbuf should not be accessed directly */
> 	fp->frags[curr_idx].mb = NULL;
> 	curr_idx = i;

Ah ok, makes sense.

> 
> 
> > If so, then it probably better to do in the same place we do
> > ip_frag_key_invalidate().
> 
> I don't feel that ip_frag_key_invalidate is the appropriate place to take care of this.  In the interest of code readability and maintainability it
> should stick to what its name implies and only invalidate the key and nothing else.    Since the ipv*_frag_reassemble() functions were
> already setup to set the pointers to NULL it should continue to be done there, but of course since it is does not handle all cases correctly it
> should be fixed.
> 
> 
> > As alternative, and probably better approach - can we modify
> > rte_ip_frag_table_destroy(), so it will free mbufs only for entires with valid
> > keys?
> 
> If you prefer this approach I can start over.

If we already doing that as you pointed above, then probably no need for new solution.
Konstantin