linux-kernel - [PATCH] infiniband: Fix a use after free in isert_connect

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Date:   Mon, 22 Mar 2021 06:53:55 -0700
From:   Lv Yunlong <lyl2019@...l.ustc.edu.cn>
To:     sagi@...mberg.me, dledford@...hat.com, jgg@...pe.ca
Cc:     linux-rdma@...r.kernel.org, target-devel@...r.kernel.org,
        linux-kernel@...r.kernel.org, Lv Yunlong <lyl2019@...l.ustc.edu.cn>
Subject: [PATCH] infiniband: Fix a use after free in isert_connect_request

The device is got by isert_device_get() with refcount is 1,
and is assigned to isert_conn by isert_conn->device = device.
When isert_create_qp() failed, device will be freed with
isert_device_put().

Later, the device is used in isert_free_login_buf(isert_conn)
by the isert_conn->device->ib_device statement. My patch
exchanges the callees order to free the device late.

Signed-off-by: Lv Yunlong <lyl2019@...l.ustc.edu.cn>
---
 drivers/infiniband/ulp/isert/ib_isert.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c
index 7305ed8976c2..d8a533e346b0 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -473,10 +473,10 @@ isert_connect_request(struct rdma_cm_id *cma_id, struct rdma_cm_event *event)
 
 out_destroy_qp:
 	isert_destroy_qp(isert_conn);
-out_conn_dev:
-	isert_device_put(device);
 out_rsp_dma_map:
 	isert_free_login_buf(isert_conn);
+out_conn_dev:
+	isert_device_put(device);
 out:
 	kfree(isert_conn);
 	rdma_reject(cma_id, NULL, 0, IB_CM_REJ_CONSUMER_DEFINED);
-- 
2.25.1