linux-kernel - [PATCH] net: 9p: Fix possible null-pointer dereference in p9_cm_event

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Date:   Tue, 10 Aug 2021 06:20:07 -0700
From:   Tuo Li <islituo@...il.com>
To:     ericvh@...il.com, lucho@...kov.net, asmadeus@...ewreck.org,
        davem@...emloft.net, kuba@...nel.org
Cc:     v9fs-developer@...ts.sourceforge.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, baijiaju1990@...il.com,
        Tuo Li <islituo@...il.com>, TOTE Robot <oslab@...nghua.edu.cn>
Subject: [PATCH] net: 9p: Fix possible null-pointer dereference in p9_cm_event_handler()

The variable rdma is checked when event->event is equal to 
RDMA_CM_EVENT_DISCONNECTED:
  if (rdma)

This indicates that it can be NULL. If so, a null-pointer dereference will 
occur when calling complete():
  complete(&rdma->cm_done);

To fix this possible null-pointer dereference, calling complete() only 
when rdma is not NULL.

Reported-by: TOTE Robot <oslab@...nghua.edu.cn>
Signed-off-by: Tuo Li <islituo@...il.com>
---
 net/9p/trans_rdma.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/9p/trans_rdma.c b/net/9p/trans_rdma.c
index af0a8a6cd3fd..fb3435dfd071 100644
--- a/net/9p/trans_rdma.c
+++ b/net/9p/trans_rdma.c
@@ -285,7 +285,8 @@ p9_cm_event_handler(struct rdma_cm_id *id, struct rdma_cm_event *event)
 	default:
 		BUG();
 	}
-	complete(&rdma->cm_done);
+	if (rdma)
+		complete(&rdma->cm_done);
 	return 0;
 }
 
-- 
2.25.1