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List:       linux-rdma
Subject:    [PATCH for-next 2/4] IB/core: Check mad_agent in ib_unregister_mad_agent before dereferencing it
From:       Or Gerlitz <ogerlitz () mellanox ! com>
Date:       2015-01-29 9:00:31
Message-ID: 1422522033-3024-3-git-send-email-ogerlitz () mellanox ! com
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From: Majd Dibbiny <majd@mellanox.com>

When ib_register_mad_agent fails, it returns a pointer with error which is not
NULL, therefore when calling ib_unregister_mad_agent we need to check that the
passed mad_agent is valid and not erroneous.

Signed-off-by: Majd Dibbiny <majd@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
---
 drivers/infiniband/core/mad.c |   25 ++++++++++++++-----------
 1 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/drivers/infiniband/core/mad.c b/drivers/infiniband/core/mad.c
index 74c30f4..13c5c47 100644
--- a/drivers/infiniband/core/mad.c
+++ b/drivers/infiniband/core/mad.c
@@ -619,18 +619,21 @@ int ib_unregister_mad_agent(struct ib_mad_agent *mad_agent)
 	struct ib_mad_agent_private *mad_agent_priv;
 	struct ib_mad_snoop_private *mad_snoop_priv;
 
-	/* If the TID is zero, the agent can only snoop. */
-	if (mad_agent->hi_tid) {
-		mad_agent_priv = container_of(mad_agent,
-					      struct ib_mad_agent_private,
-					      agent);
-		unregister_mad_agent(mad_agent_priv);
-	} else {
-		mad_snoop_priv = container_of(mad_agent,
-					      struct ib_mad_snoop_private,
-					      agent);
-		unregister_mad_snoop(mad_snoop_priv);
+	if (!IS_ERR(mad_agent)) {
+		/* If the TID is zero, the agent can only snoop. */
+		if (mad_agent->hi_tid) {
+			mad_agent_priv = container_of(mad_agent,
+						      struct ib_mad_agent_private,
+						      agent);
+			unregister_mad_agent(mad_agent_priv);
+		} else {
+			mad_snoop_priv = container_of(mad_agent,
+						      struct ib_mad_snoop_private,
+						      agent);
+			unregister_mad_snoop(mad_snoop_priv);
+		}
 	}
+
 	return 0;
 }
 EXPORT_SYMBOL(ib_unregister_mad_agent);
-- 
1.7.1

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