[openib-general] [Fwd: [PATCH] RDMA/iwcm: Fix memory leak]

[Krishna Kumar2]

That is valid only if the drivers also comply. Eg if driver has two
stack variables private_data and private_data_len, and it sets
only private_data_len to zero. Then when calling the upper layer,
it sets the event->private_data to its local private_data (uninitialized)
and event->private_data_len to its local private_data_len (zero).
Here we have to check the private_data_len before touching
private_data or risk bug/panic.

thanks,

- KK

Tom Tucker <tom at opengridcomputing.com> wrote on 11/10/2006 10:20:18 AM:

> 
> If it's truly nul or a ptr, we don't need to (and shouldn't) check, just
> call kfree. If it's unitialized, we can't tell anyway and it's a bug --
> right? 
> 
> Am I missing something?
> 
> On 11/9/06 10:41 PM, "Krishna Kumar2" <krkumar2 at in.ibm.com> wrote:
> 
> > Though the amso driver (c2_ae_event) is setting the private_data and
> > private_data_len together for connect request and connect result, so
> > the check may not be necessary. But if the semantics prefer checking
> > to make sure, we should follow that (esp if other future drivers may
> > also simply set private_data_len to zero without modifying
> > private_data).
> > 
> > I did it this way since cm_conn_rep_handler() had the same check :)
> > 
> > thanks,
> > 
> > - KK
> > 
> >> I think the semantics are that the pointer is only used if
> >> private_data_len > 0.  Otherwise, it is undefined.  So I think we 
should
> >> keep the check.  Plus I don't like calling kfree() with a NULL 
pointer.
> >> It just seems wrong...
> >> 
> >> ;-)
> >> 
> >> 
> >> On Thu, 2006-11-09 at 14:59 -0800, Roland Dreier wrote:
> >>>>>    if (iw_event->private_data_len)
> >>>>>       kfree(iw_event->private_data);
> >>>> 
> >>>> Kfree checks for a null value, so is the private_data_len check
> > necessary?
> >>> 
> >>> Could private_data be a junk pointer if private_data_len == 0 ?
> >>> 
> >>>  - R.
> >> 
> >> 
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