IB/mad: Fix error path if response alloc fails in ib_mad_recv_done_handler()

If ib_mad_recv_done_handler() fails to allocate response, then it just
printed a warning and continued, which leads to an oops if the MAD is
being handled for a switch device, because the switch code uses
response without checking for NULL.  Fix this by bailing out of the
function if the allocation fails.

Signed-off-by: Suresh Shelvapille <suri@baymicrosystems.com>
Signed-off-by: Hal Rosenstock <hal.rosenstock@gmail.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

diff --git a/drivers/infiniband/core/mad.c b/drivers/infiniband/core/mad.c
index bc547f1..9697857 100644 (file)
--- a/drivers/infiniband/core/mad.c
+++ b/drivers/infiniband/core/mad.c
@@ -1842,16 +1842,11 @@ static void ib_mad_recv_done_handler(struct ib_mad_port_private *port_priv,
 {
        struct ib_mad_qp_info *qp_info;
        struct ib_mad_private_header *mad_priv_hdr;
-       struct ib_mad_private *recv, *response;
+       struct ib_mad_private *recv, *response = NULL;
        struct ib_mad_list_head *mad_list;
        struct ib_mad_agent_private *mad_agent;
        int port_num;
 
-       response = kmem_cache_alloc(ib_mad_cache, GFP_KERNEL);
-       if (!response)
-               printk(KERN_ERR PFX "ib_mad_recv_done_handler no memory "
-                      "for response buffer\n");
-
        mad_list = (struct ib_mad_list_head *)(unsigned long)wc->wr_id;
        qp_info = mad_list->mad_queue->qp_info;
        dequeue_mad(mad_list);
@@ -1879,6 +1874,13 @@ static void ib_mad_recv_done_handler(struct ib_mad_port_private *port_priv,
        if (!validate_mad(&recv->mad.mad, qp_info->qp->qp_num))
                goto out;
 
+       response = kmem_cache_alloc(ib_mad_cache, GFP_KERNEL);
+       if (!response) {
+               printk(KERN_ERR PFX "ib_mad_recv_done_handler no memory "
+                      "for response buffer\n");
+               goto out;
+       }
+
        if (port_priv->device->node_type == RDMA_NODE_IB_SWITCH)
                port_num = wc->port_num;
        else