| Message ID | 85e04e1e6367f19c8f538d145b32f5bb93788d8a.1615199056.git.bnemeth@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | net: prevent infinite loop caused by incorrect proto from virtio_net_hdr_set_proto | expand |
On Mon, 2021-03-08 at 09:17 -0700, David Ahern wrote: > On 3/8/21 9:07 AM, Willem de Bruijn wrote: > > > diff --git a/net/mpls/mpls_gso.c b/net/mpls/mpls_gso.c > > > index b1690149b6fa..cc1b6457fc93 100644 > > > --- a/net/mpls/mpls_gso.c > > > +++ b/net/mpls/mpls_gso.c > > > @@ -27,7 +27,7 @@ static struct sk_buff *mpls_gso_segment(struct > > > sk_buff *skb, > > > > > > skb_reset_network_header(skb); > > > mpls_hlen = skb_inner_network_header(skb) - > > > skb_network_header(skb); > > > - if (unlikely(!pskb_may_pull(skb, mpls_hlen))) > > > + if (unlikely(!mpls_hlen || !pskb_may_pull(skb, > > > mpls_hlen))) > > > goto out; > > > > Good cathc. Besides length zero, this can be more strict: a label > > is > > 4B, so mpls_hlen needs to be >= 4B. > > > > Perhaps even aligned to 4B, too, but not if there may be other > > encap on top. > > > > Unfortunately there is no struct or type definition that we can use > > a > > sizeof instead of open coding the raw constant. > > > > MPLS_HLEN can be used here. > What about sizeof(struct mpls_label), like in net/ipv4/tunnel4.c?
diff --git a/net/mpls/mpls_gso.c b/net/mpls/mpls_gso.c index b1690149b6fa..cc1b6457fc93 100644 --- a/net/mpls/mpls_gso.c +++ b/net/mpls/mpls_gso.c @@ -27,7 +27,7 @@ static struct sk_buff *mpls_gso_segment(struct sk_buff *skb, skb_reset_network_header(skb); mpls_hlen = skb_inner_network_header(skb) - skb_network_header(skb); - if (unlikely(!pskb_may_pull(skb, mpls_hlen))) + if (unlikely(!mpls_hlen || !pskb_may_pull(skb, mpls_hlen))) goto out; /* Setup inner SKB. */
A packet with skb_inner_network_header(skb) == skb_network_header(skb) and ETH_P_MPLS_UC will prevent mpls_gso_segment from pulling any headers from the packet. Subsequently, the call to skb_mac_gso_segment will again call mpls_gso_segment with the same packet leading to an infinite loop. Signed-off-by: Balazs Nemeth <bnemeth@redhat.com> --- net/mpls/mpls_gso.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)