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From:   Lv Yunlong <lyl2019@mail.ustc.edu.cn>
To:     faisal.latif@intel.com, shiraz.saleem@intel.com,
        dledford@redhat.com, jgg@ziepe.ca
Cc:     linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org,
        Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Subject: [PATCH] infiniband/i40iw: Fix a use after free in i40iw_cm_event_handler
Date:   Wed, 10 Mar 2021 19:14:14 -0800
Message-Id: <20210311031414.5011-1-lyl2019@mail.ustc.edu.cn>
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In the case of I40IW_CM_EVENT_ABORTED, i40iw_event_connect_error()
could be called to free the event->cm_node. However, event->cm_node
will be used after and cause use after free. It needs to add flags
to inform that event->cm_node has been freed.

Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
---
 drivers/infiniband/hw/i40iw/i40iw_cm.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/i40iw/i40iw_cm.c b/drivers/infiniband/hw/i40iw/i40iw_cm.c
index ac65c8237b2e..447b43c2d21f 100644
--- a/drivers/infiniband/hw/i40iw/i40iw_cm.c
+++ b/drivers/infiniband/hw/i40iw/i40iw_cm.c
@@ -4175,6 +4175,7 @@ static void i40iw_cm_event_handler(struct work_struct *work)
 						    struct i40iw_cm_event,
 						    event_work);
 	struct i40iw_cm_node *cm_node;
+	int flags = 0;
 
 	if (!event || !event->cm_node || !event->cm_node->cm_core)
 		return;
@@ -4211,6 +4212,7 @@ static void i40iw_cm_event_handler(struct work_struct *work)
 		    (event->cm_node->state == I40IW_CM_STATE_OFFLOADED))
 			break;
 		i40iw_event_connect_error(event);
+		flags = 1;
 		break;
 	default:
 		i40iw_pr_err("event type = %d\n", event->type);
@@ -4218,7 +4220,8 @@ static void i40iw_cm_event_handler(struct work_struct *work)
 	}
 
 	event->cm_info.cm_id->rem_ref(event->cm_info.cm_id);
-	i40iw_rem_ref_cm_node(event->cm_node);
+	if (!flags)
+		i40iw_rem_ref_cm_node(event->cm_node);
 	kfree(event);
 }
 
-- 
2.25.1