Re: [PATCH] RDS: fix race condition when sending a message on unbound socket.

[santosh shilimkar]

On 11/3/2015 3:25 AM, Quentin Casasnovas wrote:
> On Fri, Oct 16, 2015 at 10:47:49AM -0700, santosh shilimkar wrote:
> > On 10/16/2015 8:11 AM, Quentin Casasnovas wrote:
> > > Sasha's found a NULL pointer dereference in the RDS connection code when
> > > sending a message to an apparently unbound socket.  The problem is caused
> > > by the code checking if the socket is bound in rds_sendmsg(), which checks
> > > the rs_bound_addr field without taking a lock on the socket.  This opens a
> > > race where rs_bound_addr is temporarily set but where the transport is not
> > > in rds_bind(), leading to a NULL pointer dereference when trying to
> > > dereference 'trans' in __rds_conn_create().
> > >
> > > Vegard wrote a reproducer for this issue, so kindly ask him to share if
> > > you're interested.
> > >
> > > I cannot reproduce the NULL pointer dereference using Vegard's reproducer
> > > with this patch, whereas I could without.
> > >
> > > Complete earlier incomplete fix to CVE-2015-6937:
> > >
> > >     74e98eb08588 ("RDS: verify the underlying transport exists before creating a connection")
>
> For reference, this has been assigned CVE-2015-7990 on the oss-sec thread:
>
>    http://seclists.org/oss-sec/2015/q4/179
New CVE number than the older one. Thanks for the note.

Regards,
Santosh
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