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>

diff --git a/drivers/infiniband/core/mad.c b/drivers/infiniband/core/mad.c
index 5c54fc2..735ad4e 100644 (file)
--- 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);
        }