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From:   Jia-Ju Bai <baijiaju1990@gmail.com>
To:     bharat@chelsio.com, dledford@redhat.com, jgg@ziepe.ca
Cc:     linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org,
        Jia-Ju Bai <baijiaju1990@gmail.com>
Subject: [PATCH] infiniband: hw: cxgb3: Fix a possible null-pointer dereference in connect_reply_upcall()
Date:   Thu, 25 Jul 2019 20:15:08 +0800
Message-Id: <20190725121508.16352-1-baijiaju1990@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

In connect_reply_upcall(), there is an if statement on line 730 to check
whether ep->com.cm_id is NULL:
    if (ep->com.cm_id)

When ep->com.cm_id is NULL, it is used on line 736:
    ep->com.cm_id->rem_ref(ep->com.cm_id);

Thus, a possible null-pointer dereference may occur.

To fix this bug, ep->com.cm_id is checked before being used.

This bug is found by a static analysis tool STCheck written by us.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
 drivers/infiniband/hw/cxgb3/iwch_cm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/cxgb3/iwch_cm.c b/drivers/infiniband/hw/cxgb3/iwch_cm.c
index 0bca72cb4d9a..2b31c4726d3e 100644
--- a/drivers/infiniband/hw/cxgb3/iwch_cm.c
+++ b/drivers/infiniband/hw/cxgb3/iwch_cm.c
@@ -733,7 +733,8 @@ static void connect_reply_upcall(struct iwch_ep *ep, int status)
 		ep->com.cm_id->event_handler(ep->com.cm_id, &event);
 	}
 	if (status < 0) {
-		ep->com.cm_id->rem_ref(ep->com.cm_id);
+		if (ep->com.cm_id)
+			ep->com.cm_id->rem_ref(ep->com.cm_id);
 		ep->com.cm_id = NULL;
 		ep->com.qp = NULL;
 	}
-- 
2.17.0