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>

1 files changed, 8 insertions, 6 deletions

diff --git a/drivers/infiniband/core/mad.c b/drivers/infiniband/core/mad.c
index bc547f1d34ba..969785762052 100644
--- 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