[PATCH 4.9 182/310] RDMA/iw_cxgb4: Avoid touch after free error in ARP failure handlers

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Raju Rangoju <rajur@xxxxxxxxxxx>


[ 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.carpenter@xxxxxxxxxx>
Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Raju Rangoju <rajur@xxxxxxxxxxx>
Reviewed-by: Steve Wise <swise@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/infiniband/hw/cxgb4/cm.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- 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
 
 	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
 	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 *hand
 
 	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)