svn commit: r272089 - head/sys/netpfil/ipfw

[Gleb Smirnoff]

On Wed, Sep 24, 2014 at 07:40:23PM -0700, Adrian Chadd wrote:
A> Hm, I saw this from Kate on IRC. Did anyone figure out _where_ these
A> frames are coming from?
A> 
A> Just dropping them is cool, but I'd really like to see the contents of
A> the frames and what their origin is.
A> 
A> I'm worried that they're valid stack-generated frames..

I agree on this. Fixing NULL pointer derefs with NULL check is not
always a right thing to do.

A> -a
A> 
A> 
A> On 24 September 2014 19:26, Sean Bruno <sbruno at freebsd.org> wrote:
A> > Author: sbruno
A> > Date: Thu Sep 25 02:26:05 2014
A> > New Revision: 272089
A> > URL: http://svnweb.freebsd.org/changeset/base/272089
A> >
A> > Log:
A> >   Fix NULL pointer deref in ipfw when using dummynet at layer 2.
A> >   Drop packet if pkg->ifp is NULL, which is the case here.
A> >
A> >   ref. https://github.com/HardenedBSD/hardenedBSD
A> >   commit 4eef3881c64f6e3aa38eebbeaf27a947a5d47dd7
A> >
A> >   PR 193861 --  DUMMYNET LAYER2: kernel panic
A> >
A> >   in this case a kernel panic occurs. Hence, when we do not get an interface,
A> >   we just drop the packet in question.
A> >
A> >   PR:           193681
A> >   Submitted by: David Carlier <david.carlier at hardenedbsd.org>
A> >   Obtained from:        Hardened BSD
A> >   MFC after:    2 weeks
A> >   Relnotes:     yes
A> >
A> > Modified:
A> >   head/sys/netpfil/ipfw/ip_dn_io.c
A> >
A> > Modified: head/sys/netpfil/ipfw/ip_dn_io.c
A> > ==============================================================================
A> > --- head/sys/netpfil/ipfw/ip_dn_io.c    Wed Sep 24 22:58:10 2014        (r272088)
A> > +++ head/sys/netpfil/ipfw/ip_dn_io.c    Thu Sep 25 02:26:05 2014        (r272089)
A> > @@ -751,10 +751,15 @@ dummynet_send(struct mbuf *m)
A> >                         /* extract the dummynet info, rename the tag
A> >                          * to carry reinject info.
A> >                          */
A> > -                       dst = pkt->dn_dir;
A> > -                       ifp = pkt->ifp;
A> > -                       tag->m_tag_cookie = MTAG_IPFW_RULE;
A> > -                       tag->m_tag_id = 0;
A> > +                       if (pkt->dn_dir == (DIR_OUT | PROTO_LAYER2) &&
A> > +                               pkt->ifp == NULL) {
A> > +                               dst = DIR_DROP;
A> > +                       } else {
A> > +                               dst = pkt->dn_dir;
A> > +                               ifp = pkt->ifp;
A> > +                               tag->m_tag_cookie = MTAG_IPFW_RULE;
A> > +                               tag->m_tag_id = 0;
A> > +                       }
A> >                 }
A> >
A> >                 switch (dst) {
A> >
A> 

-- 
Totus tuus, Glebius.