RDMA: Fix use-after-free in rxe_queue_cleanup

On error handling path in rxe_qp_from_init() qp->sq.queue is freed and
then rxe_create_qp() will drop last reference to this object. qp clean up
function will try to free this queue one time and it causes UAF bug.

Fix it by zeroing queue pointer after freeing queue in rxe_qp_from_init().

Fixes: 514aee6 ("RDMA: Globally allocate and release QP memory")
Link: https://lore.kernel.org/r/[email protected]
Reported-by: [email protected]
Signed-off-by: Pavel Skripkin <[email protected]>
Reviewed-by: Zhu Yanjun <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>

Author: pskrgag

drivers/infiniband/sw/rxe/rxe_qp.c

@@ -359,6 +359,7 @@ int rxe_qp_from_init(struct rxe_dev *rxe, struct rxe_qp *qp, struct rxe_pd *pd,
 
 err2:
 	rxe_queue_cleanup(qp->sq.queue);
+	qp->sq.queue = NULL;
 err1:
 	qp->pd = NULL;
 	qp->rcq = NULL;