From: Zhu Yanjun <yanjun.zhu@linux.dev>
Date: Tue, 5 Jul 2022 18:54:14 -0400
Subject: RDMA/rxe: Fix BUG: KASAN: null-ptr-deref in rxe_qp_do_cleanup
Patch-mainline: v6.0-rc1
Git-commit: 37da51efe6eaa0560f46803c8c436a48a2084da7
References: jsc#PED-1111

The function rxe_create_qp calls rxe_qp_from_init. If some error
occurs, the error handler of function rxe_qp_from_init will set
both scq and rcq to NULL.

Then rxe_create_qp calls rxe_put to handle qp. In the end,
rxe_qp_do_cleanup is called by rxe_put. rxe_qp_do_cleanup directly
accesses scq and rcq before checking them. This will cause
null-ptr-deref error.

The call graph is as below:

rxe_create_qp {
  ...
  rxe_qp_from_init {
    ...
  err1:
    ...
    qp->rcq = NULL;  <---rcq is set to NULL
    qp->scq = NULL;  <---scq is set to NULL
    ...
  }

qp_init:
  rxe_put{
    ...
    rxe_qp_do_cleanup {
      ...
      atomic_dec(&qp->scq->num_wq); <--- scq is accessed
      ...
      atomic_dec(&qp->rcq->num_wq); <--- rcq is accessed
    }
}

Fixes: 4703b4f0d94a ("RDMA/rxe: Enforce IBA C11-17")
Link: https://lore.kernel.org/r/20220705225414.315478-1-yanjun.zhu@linux.dev
Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Reviewed-by: Bob Pearson <rpearsonhpe@gmail.com>
Reviewed-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/infiniband/sw/rxe/rxe_qp.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/drivers/infiniband/sw/rxe/rxe_qp.c
+++ b/drivers/infiniband/sw/rxe/rxe_qp.c
@@ -802,13 +802,15 @@ static void rxe_qp_do_cleanup(struct wor
 	if (qp->rq.queue)
 		rxe_queue_cleanup(qp->rq.queue);
 
-	atomic_dec(&qp->scq->num_wq);
-	if (qp->scq)
+	if (qp->scq) {
+		atomic_dec(&qp->scq->num_wq);
 		rxe_put(qp->scq);
+	}
 
-	atomic_dec(&qp->rcq->num_wq);
-	if (qp->rcq)
+	if (qp->rcq) {
+		atomic_dec(&qp->rcq->num_wq);
 		rxe_put(qp->rcq);
+	}
 
 	if (qp->pd)
 		rxe_put(qp->pd);