[PATCH 1/1] RDMA/rxe: Fix the use-before-initialization error of resp_pkts

[Zhu Yanjun <yanjun.zhu@xxxxxxxxx>]

From: Zhu Yanjun <yanjun.zhu@xxxxxxxxx>

In the following:
"
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
 assign_lock_key kernel/locking/lockdep.c:982 [inline]
 register_lock_class+0xdb6/0x1120 kernel/locking/lockdep.c:1295
 __lock_acquire+0x10a/0x5df0 kernel/locking/lockdep.c:4951
 lock_acquire kernel/locking/lockdep.c:5691 [inline]
 lock_acquire+0x1b1/0x520 kernel/locking/lockdep.c:5656
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x3d/0x60 kernel/locking/spinlock.c:162
 skb_dequeue+0x20/0x180 net/core/skbuff.c:3639
 drain_resp_pkts drivers/infiniband/sw/rxe/rxe_comp.c:555 [inline]
 rxe_completer+0x250d/0x3cc0 drivers/infiniband/sw/rxe/rxe_comp.c:652
 rxe_qp_do_cleanup+0x1be/0x820 drivers/infiniband/sw/rxe/rxe_qp.c:761
 execute_in_process_context+0x3b/0x150 kernel/workqueue.c:3473
 __rxe_cleanup+0x21e/0x370 drivers/infiniband/sw/rxe/rxe_pool.c:233
 rxe_create_qp+0x3f6/0x5f0 drivers/infiniband/sw/rxe/rxe_verbs.c:583
...
"
This is a use-before-initialization problem.

In the following function
"
291 /* called by the create qp verb */
292 int rxe_qp_from_init(struct rxe_dev *rxe, struct rxe_qp *qp,
struct rxe_pd *pd,
297 {
            ...
317         rxe_qp_init_misc(rxe, qp, init);
            ...
322
323         err = rxe_qp_init_resp(rxe, qp, init, udata, uresp);
324         if (err)
325                 goto err2;   <--- error

            ...

334 err2:
335         rxe_queue_cleanup(qp->sq.queue); <--- Goto here
336         qp->sq.queue = NULL;
"
In rxe_qp_init_resp, the error occurs before skb_queue_head_init.
So this call trace appeared.

Reported-by: syzbot+eba589d8f49c73d356da@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Zhu Yanjun <yanjun.zhu@xxxxxxxxx>
---
 drivers/infiniband/sw/rxe/rxe_qp.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/infiniband/sw/rxe/rxe_qp.c b/drivers/infiniband/sw/rxe/rxe_qp.c
index c5451a4488ca..22ef6188d7b1 100644
--- a/drivers/infiniband/sw/rxe/rxe_qp.c
+++ b/drivers/infiniband/sw/rxe/rxe_qp.c
@@ -176,6 +176,9 @@ static void rxe_qp_init_misc(struct rxe_dev *rxe, struct rxe_qp *qp,
 	spin_lock_init(&qp->rq.producer_lock);
 	spin_lock_init(&qp->rq.consumer_lock);
 
+	skb_queue_head_init(&qp->req_pkts);
+	skb_queue_head_init(&qp->resp_pkts);
+
 	atomic_set(&qp->ssn, 0);
 	atomic_set(&qp->skb_out, 0);
 }
@@ -234,8 +237,6 @@ static int rxe_qp_init_req(struct rxe_dev *rxe, struct rxe_qp *qp,
 	qp->req.opcode		= -1;
 	qp->comp.opcode		= -1;
 
-	skb_queue_head_init(&qp->req_pkts);
-
 	rxe_init_task(&qp->req.task, qp, rxe_requester);
 	rxe_init_task(&qp->comp.task, qp, rxe_completer);
 
@@ -279,8 +280,6 @@ static int rxe_qp_init_resp(struct rxe_dev *rxe, struct rxe_qp *qp,
 		}
 	}
 
-	skb_queue_head_init(&qp->resp_pkts);
-
 	rxe_init_task(&qp->resp.task, qp, rxe_responder);
 
 	qp->resp.opcode		= OPCODE_NONE;
-- 
2.27.0