On Thu, Aug 20, 2020 at 10:09:02AM +0200, Greg KH wrote:
> On Wed, Aug 19, 2020 at 09:11:17PM +0100, Alessio Balsini wrote:
> > From: WANG Cong <xiyou.wangcong@xxxxxxxxx>
> >
> > [ Upstream commit 199ab00f3cdb6f154ea93fa76fd80192861a821d ]
> >
> > Andrey reported a out-of-bound access in ip6_tnl_xmit(), this
> > is because we use an ipv4 dst in ip6_tnl_xmit() and cast an IPv4
> > neigh key as an IPv6 address:
> >
> > neigh = dst_neigh_lookup(skb_dst(skb),
> > &ipv6_hdr(skb)->daddr);
> > if (!neigh)
> > goto tx_err_link_failure;
> >
> > addr6 = (struct in6_addr *)&neigh->primary_key; // <=== HERE
> > addr_type = ipv6_addr_type(addr6);
> >
> > if (addr_type == IPV6_ADDR_ANY)
> > addr6 = &ipv6_hdr(skb)->daddr;
> >
> > memcpy(&fl6->daddr, addr6, sizeof(fl6->daddr));
> >
> > Also the network header of the skb at this point should be still IPv4
> > for 4in6 tunnels, we shold not just use it as IPv6 header.
> >
> > This patch fixes it by checking if skb->protocol is ETH_P_IPV6: if it
> > is, we are safe to do the nexthop lookup using skb_dst() and
> > ipv6_hdr(skb)->daddr; if not (aka IPv4), we have no clue about which
> > dest address we can pick here, we have to rely on callers to fill it
> > from tunnel config, so just fall to ip6_route_output() to make the
> > decision.
> >
> > Fixes: ea3dc9601bda ("ip6_tunnel: Add support for wildcard tunnel endpoints.")
> > Reported-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> > Reported-by: syzbot+01400f5fc51cf4747bec@xxxxxxxxxxxxxxxxxxxxxxxxx
> > Tested-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> > Cc: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
> > Signed-off-by: Cong Wang <xiyou.wangcong@xxxxxxxxx>
> > Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Alessio Balsini <balsini@xxxxxxxxxxx>
> > ---
> > net/ipv6/ip6_tunnel.c | 32 +++++++++++++++++---------------
> > 1 file changed, 17 insertions(+), 15 deletions(-)
>
> This was already applied to the 4.4.66 kernel release
>
> But this patch applies to the 4.4.y tree. Which is really really odd,
> what is going on here?
>
> confused,
>
> greg k-h
Totally odd... Now that you gave me this heads up, I can see that the
patch was applied to v4.4.66 and for some reason dropped since v4.4.118.
Can you please take a look? Thanks!
Alessio
