net: ovs: flow: fix potential illegal memory access in __parse_flow_nlattrs

In function __parse_flow_nlattrs(), we check for condition
(type > OVS_KEY_ATTR_MAX) and if true, print an error, but we do
not return from this function as in other checks. It seems this
has been forgotten, as otherwise, we could access beyond the
memory of ovs_key_lens, which is of ovs_key_lens[OVS_KEY_ATTR_MAX + 1].
Hence, a maliciously prepared nla_type from user space could access
beyond this upper limit.

Introduced by 03f0d916a ("openvswitch: Mega flow implementation").

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Andy Zhou <azhou@nicira.com>
Acked-by: Jesse Gross <jesse@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c
index fb36f856516112045c767f02a7f561da2a85d086..410db90db73d32493a525a530cd04ad57a92fadf 100644 (file)
--- a/net/openvswitch/flow.c
+++ b/net/openvswitch/flow.c
@@ -1178,6 +1178,7 @@ static int __parse_flow_nlattrs(const struct nlattr *attr,
                if (type > OVS_KEY_ATTR_MAX) {
                        OVS_NLERR("Unknown key attribute (type=%d, max=%d).\n",
                                  type, OVS_KEY_ATTR_MAX);
+                       return -EINVAL;
                }
 
                if (attrs & (1 << type)) {