IB/mad: Fix null pointer dereference in local_completions()

handle_outgoing_dr_smp() can queue a struct ib_mad_local_private
*local on the mad_agent_priv->local_work work queue with
local->mad_priv == NULL if device->process_mad() returns
IB_MAD_RESULT_SUCCESS | IB_MAD_RESULT_REPLY and
(!ib_response_mad(&mad_priv->mad.mad) ||
!mad_agent_priv->agent.recv_handler).

In this case, local_completions() will be called with local->mad_priv
== NULL. The code does check for this case and skips calling
recv_mad_agent->agent.recv_handler() but recv == 0 so
kmem_cache_free() is called with a NULL pointer.

Also, since recv isn't reinitialized each time through the loop, it
can cause a memory leak if recv should have been zero.

Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/infiniband/core/mad.c b/drivers/infiniband/core/mad.c
index 5c54fc2350be..735ad4ea10f0 100644
--- a/drivers/infiniband/core/mad.c
+++ b/drivers/infiniband/core/mad.c
@@ -2356,7 +2356,7 @@ static void local_completions(struct work_struct *work)
         struct ib_mad_local_private *local;
         struct ib_mad_agent_private *recv_mad_agent;
         unsigned long flags;
-        int recv = 0;
+        int free_mad;
         struct ib_wc wc;
         struct ib_mad_send_wc mad_send_wc;
 
@@ -2370,14 +2370,15 @@ static void local_completions(struct work_struct *work)
                                    completion_list);
                 list_del(&local->completion_list);
                 spin_unlock_irqrestore(&mad_agent_priv->lock, flags);
+                free_mad = 0;
                 if (local->mad_priv) {
                         recv_mad_agent = local->recv_mad_agent;
                         if (!recv_mad_agent) {
                                 printk(KERN_ERR PFX "No receive MAD agent for local completion\n");
+                                free_mad = 1;
                                 goto local_send_completion;
                         }
 
-                        recv = 1;
                         /*
                          * Defined behavior is to complete response
                          * before request
@@ -2422,7 +2423,7 @@ local_send_completion:
 
                 spin_lock_irqsave(&mad_agent_priv->lock, flags);
                 atomic_dec(&mad_agent_priv->refcount);
-                if (!recv)
+                if (free_mad)
                         kmem_cache_free(ib_mad_cache, local->mad_priv);
                 kfree(local);
         }