[PATCH for-next v2 2/3] RDMA/rxe: Fix unsafe drain work queue code

[Bob Pearson <rpearsonhpe@gmail.com>]

If create_qp does not fully succeed it is possible for qp cleanup
code to attempt to drain the send or recv work queues before the
queues have been created causing a seg fault. This patch checks
to see if the queues exist before attempting to drain them.

Reported-by: syzbot+2da1965168e7dbcba136@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-rdma/00000000000012d89205fe7cfe00@google.com/raw
Fixes: 49dc9c1f0c7e ("RDMA/rxe: Cleanup reset state handling in rxe_resp.c")
Fixes: fbdeb828a21f ("RDMA/rxe: Cleanup error state handling in rxe_comp.c")
Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
---
 drivers/infiniband/sw/rxe/rxe_comp.c | 4 ++++
 drivers/infiniband/sw/rxe/rxe_resp.c | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/drivers/infiniband/sw/rxe/rxe_comp.c b/drivers/infiniband/sw/rxe/rxe_comp.c
index 0c0ae214c3a9..c2a53418a9ce 100644
--- a/drivers/infiniband/sw/rxe/rxe_comp.c
+++ b/drivers/infiniband/sw/rxe/rxe_comp.c
@@ -594,6 +594,10 @@ static void flush_send_queue(struct rxe_qp *qp, bool notify)
 	struct rxe_queue *q = qp->sq.queue;
 	int err;
 
+	/* send queue never got created. nothing to do. */
+	if (!qp->sq.queue)
+		return;
+
 	while ((wqe = queue_head(q, q->type))) {
 		if (notify) {
 			err = flush_send_wqe(qp, wqe);
diff --git a/drivers/infiniband/sw/rxe/rxe_resp.c b/drivers/infiniband/sw/rxe/rxe_resp.c
index 8a3c9c2c5a2d..9b4f95820b40 100644
--- a/drivers/infiniband/sw/rxe/rxe_resp.c
+++ b/drivers/infiniband/sw/rxe/rxe_resp.c
@@ -1467,6 +1467,10 @@ static void flush_recv_queue(struct rxe_qp *qp, bool notify)
 		return;
 	}
 
+	/* recv queue not created. nothing to do. */
+	if (!qp->rq.queue)
+		return;
+
 	while ((wqe = queue_head(q, q->type))) {
 		if (notify) {
 			err = flush_recv_wqe(qp, wqe);
-- 
2.39.2