[PATCH 4.14 088/189] IB/rxe: avoid double kfree_skb

Greg Kroah-Hartman
2018-06-18T08:33:16Z

From: Zhu Yanjun <yanjun.zhu@oracle.com>

[ Upstream commit 9fd4350ba8953804f05215999e11a6cfb7b41f2b ]

When skb is sent, it will pass the following functions in soft roce.

rxe_send [rdma_rxe]
ip_local_out
__ip_local_out
ip_output
ip_finish_output
ip_finish_output2
dev_queue_xmit
__dev_queue_xmit
dev_hard_start_xmit

In the above functions, if error occurs in the above functions or
iptables rules drop skb after ip_local_out, kfree_skb will be called.
So it is not necessary to call kfree_skb in soft roce module again.
Or else crash will occur.

The steps to reproduce:

server client
--------- ---------
|1.1.1.1|<----rxe-channel--->|1.1.1.2|
--------- ---------

On server: rping -s -a 1.1.1.1 -v -C 10000 -S 512
On client: rping -c -a 1.1.1.1 -v -C 10000 -S 512

The kernel configs CONFIG_DEBUG_KMEMLEAK and
CONFIG_DEBUG_OBJECTS are enabled on both server and client.

When rping runs, run the following command in server:

iptables -I OUTPUT -p udp --dport 4791 -j DROP

Without this patch, crash will occur.

CC: Srinivas Eeda <srinivas.eeda@oracle.com>
CC: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Zhu Yanjun <yanjun.zhu@oracle.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/infiniband/sw/rxe/rxe_req.c | 1 -
drivers/infiniband/sw/rxe/rxe_resp.c | 6 +-----
2 files changed, 1 insertion(+), 6 deletions(-)

--- a/drivers/infiniband/sw/rxe/rxe_req.c
+++ b/drivers/infiniband/sw/rxe/rxe_req.c
@@ -728,7 +728,6 @@ next_wqe:
rollback_state(wqe, qp, &rollback_wqe, rollback_psn);

if (ret == -EAGAIN) {
- kfree_skb(skb);
rxe_run_task(&qp->req.task, 1);
goto exit;
}
--- a/drivers/infiniband/sw/rxe/rxe_resp.c
+++ b/drivers/infiniband/sw/rxe/rxe_resp.c
@@ -742,7 +742,6 @@ static enum resp_states read_reply(struc
err = rxe_xmit_packet(rxe, qp, &ack_pkt, skb);
if (err) {
pr_err("Failed sending RDMA reply.\n");
- kfree_skb(skb);
return RESPST_ERR_RNR;
}

@@ -955,10 +954,8 @@ static int send_ack(struct rxe_qp *qp, s
}

err = rxe_xmit_packet(rxe, qp, &ack_pkt, skb);
- if (err) {
+ if (err)
pr_err_ratelimited("Failed sending ack\n");
- kfree_skb(skb);
- }

err1:
return err;
@@ -1151,7 +1148,6 @@ static enum resp_states duplicate_reques
if (rc) {
pr_err("Failed resending result. This flow is not handled - skb ignored\n");
rxe_drop_ref(qp);
- kfree_skb(skb_copy);
rc = RESPST_CLEANUP;
goto out;
}