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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Dan Carpenter <dan.carpenter@oracle.com>,
        Raju Rangoju <rajur@chelsio.com>,
        Jason Gunthorpe <jgg@mellanox.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 130/639] RDMA/iw_cxgb4: Fix the unchecked ep dereference
Date:   Fri, 24 Jan 2020 10:25:00 +0100
Message-Id: <20200124093103.576206377@linuxfoundation.org>
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From: Raju Rangoju <rajur@chelsio.com>

[ Upstream commit 3352976c892301fd576a2e9ff0ac7337b2e2ca48 ]

The patch 944661dd97f4: "RDMA/iw_cxgb4: atomically lookup ep and get a
reference" from May 6, 2016, leads to the following Smatch complaint:

    drivers/infiniband/hw/cxgb4/cm.c:2953 terminate()
    error: we previously assumed 'ep' could be null (see line 2945)

Fixes: 944661dd97f4 ("RDMA/iw_cxgb4: atomically lookup ep and get a reference")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Raju Rangoju <rajur@chelsio.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/infiniband/hw/cxgb4/cm.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/infiniband/hw/cxgb4/cm.c b/drivers/infiniband/hw/cxgb4/cm.c
index 4dcc92d116097..1b3d014fa1d6e 100644
--- a/drivers/infiniband/hw/cxgb4/cm.c
+++ b/drivers/infiniband/hw/cxgb4/cm.c
@@ -2947,15 +2947,18 @@ static int terminate(struct c4iw_dev *dev, struct sk_buff *skb)
 
 	ep = get_ep_from_tid(dev, tid);
 
-	if (ep && ep->com.qp) {
-		pr_warn("TERM received tid %u qpid %u\n",
-			tid, ep->com.qp->wq.sq.qid);
-		attrs.next_state = C4IW_QP_STATE_TERMINATE;
-		c4iw_modify_qp(ep->com.qp->rhp, ep->com.qp,
-			       C4IW_QP_ATTR_NEXT_STATE, &attrs, 1);
+	if (ep) {
+		if (ep->com.qp) {
+			pr_warn("TERM received tid %u qpid %u\n", tid,
+				ep->com.qp->wq.sq.qid);
+			attrs.next_state = C4IW_QP_STATE_TERMINATE;
+			c4iw_modify_qp(ep->com.qp->rhp, ep->com.qp,
+				       C4IW_QP_ATTR_NEXT_STATE, &attrs, 1);
+		}
+
+		c4iw_put_ep(&ep->com);
 	} else
 		pr_warn("TERM received tid %u no ep/qp\n", tid);
-	c4iw_put_ep(&ep->com);
 
 	return 0;
 }
-- 
2.20.1