[PATCH AUTOSEL for 4.9 187/281] RDMA/iw_cxgb4: Avoid touch after free error in ARP failure handlers

[Sasha Levin]

From: Raju Rangoju <ra...@chelsio.com>

[ Upstream commit 1dad0ebeea1cd890b8892523f736916e245b0aef ]

The patch 761e19a504af (RDMA/iw_cxgb4: Handle return value of
c4iw_ofld_send() in abort_arp_failure()) from May 6, 2016
leads to the following static checker warning:
        drivers/infiniband/hw/cxgb4/cm.c:575 abort_arp_failure()
        warn: passing freed memory 'skb'

Also fixes skb leak when l2t resolution fails

Fixes: 761e19a504afa55 (RDMA/iw_cxgb4: Handle return value of
c4iw_ofld_send() in abort_arp_failure())
Reported-by: Dan Carpenter <dan.carpen...@oracle.com>
Cc: Dan Carpenter <dan.carpen...@oracle.com>
Signed-off-by: Raju Rangoju <ra...@chelsio.com>
Reviewed-by: Steve Wise <sw...@opengridcomputing.com>
Signed-off-by: Doug Ledford <dledf...@redhat.com>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
---
 drivers/infiniband/hw/cxgb4/cm.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/cxgb4/cm.c b/drivers/infiniband/hw/cxgb4/cm.c
index 6512a555f7f8..dd18b74cd01d 100644
--- a/drivers/infiniband/hw/cxgb4/cm.c
+++ b/drivers/infiniband/hw/cxgb4/cm.c
@@ -488,6 +488,7 @@ static int _put_ep_safe(struct c4iw_dev *dev, struct 
sk_buff *skb)
 
        ep = *((struct c4iw_ep **)(skb->cb + 2 * sizeof(void *)));
        release_ep_resources(ep);
+       kfree_skb(skb);
        return 0;
 }
 
@@ -498,6 +499,7 @@ static int _put_pass_ep_safe(struct c4iw_dev *dev, struct 
sk_buff *skb)
        ep = *((struct c4iw_ep **)(skb->cb + 2 * sizeof(void *)));
        c4iw_put_ep(&ep->parent_ep->com);
        release_ep_resources(ep);
+       kfree_skb(skb);
        return 0;
 }
 
@@ -569,11 +571,13 @@ static void abort_arp_failure(void *handle, struct 
sk_buff *skb)
 
        PDBG("%s rdev %p\n", __func__, rdev);
        req->cmd = CPL_ABORT_NO_RST;
+       skb_get(skb);
        ret = c4iw_ofld_send(rdev, skb);
        if (ret) {
                __state_set(&ep->com, DEAD);
                queue_arp_failure_cpl(ep, skb, FAKE_CPL_PUT_EP_SAFE);
-       }
+       } else
+               kfree_skb(skb);
 }
 
 static int send_flowc(struct c4iw_ep *ep)
-- 
2.14.1