RDS/IB: Improve RDS protocol version checking

RDS on IB uses privdata to do protocol version negotiation. Apparently
the IB stack will return a larger privdata buffer than the struct we were
expecting. Just to be extra-sure, this patch adds some checks in this area.

Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 6 deletions

diff --git a/net/rds/ib_cm.c b/net/rds/ib_cm.c
index 605c032ed5d5..0964ac533ec8 100644
--- a/net/rds/ib_cm.c
+++ b/net/rds/ib_cm.c
@@ -98,7 +98,7 @@ void rds_ib_cm_connect_complete(struct rds_connection *conn, struct rdma_cm_even
         struct ib_qp_attr qp_attr;
         int err;
 
-        if (event->param.conn.private_data_len) {
+        if (event->param.conn.private_data_len >= sizeof(*dp)) {
                 dp = event->param.conn.private_data;
 
                 rds_ib_set_protocol(conn,
@@ -344,19 +344,32 @@ out:
         return ret;
 }
 
-static u32 rds_ib_protocol_compatible(const struct rds_ib_connect_private *dp)
+static u32 rds_ib_protocol_compatible(struct rdma_cm_event *event)
 {
+        const struct rds_ib_connect_private *dp = event->param.conn.private_data;
         u16 common;
         u32 version = 0;
 
-        /* rdma_cm private data is odd - when there is any private data in the
+        /*
+         * rdma_cm private data is odd - when there is any private data in the
          * request, we will be given a pretty large buffer without telling us the
          * original size. The only way to tell the difference is by looking at
          * the contents, which are initialized to zero.
          * If the protocol version fields aren't set, this is a connection attempt
          * from an older version. This could could be 3.0 or 2.0 - we can't tell.
-         * We really should have changed this for OFED 1.3 :-( */
-        if (dp->dp_protocol_major == 0)
+         * We really should have changed this for OFED 1.3 :-(
+         */
+
+        /* Be paranoid. RDS always has privdata */
+        if (!event->param.conn.private_data_len) {
+                printk(KERN_NOTICE "RDS incoming connection has no private data, "
+                        "rejecting\n");
+                return 0;
+        }
+
+        /* Even if len is crap *now* I still want to check it. -ASG */
+        if (event->param.conn.private_data_len < sizeof (*dp)
+            || dp->dp_protocol_major == 0)
                 return RDS_PROTOCOL_3_0;
 
         common = be16_to_cpu(dp->dp_protocol_minor_mask) & RDS_IB_SUPPORTED_PROTOCOLS;
@@ -388,7 +401,7 @@ int rds_ib_cm_handle_connect(struct rdma_cm_id *cm_id,
         int err, destroy = 1;
 
         /* Check whether the remote protocol version matches ours. */
-        version = rds_ib_protocol_compatible(dp);
+        version = rds_ib_protocol_compatible(event);
         if (!version)
                 goto out;