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From:   Wang Ming <machel@vivo.com>
To:     Christine Caulfield <ccaulfie@redhat.com>,
        David Teigland <teigland@redhat.com>, cluster-devel@redhat.com,
        linux-kernel@vger.kernel.org
Cc:     opensource.kernel@vivo.com, Wang Ming <machel@vivo.com>
Subject: [PATCH v1] fs:dlm:Fix NULL pointer dereference bug in accept_from_sock()
Date:   Tue,  4 Jul 2023 18:47:16 +0800
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newcon -> sock is NULL but dereferenced.
First check newcon. Whether sock is a null pointer.
If so, the subsequent operations are skipped.
If it is not empty, perform subsequent operations.

Signed-off-by: Wang Ming <machel@vivo.com>
---
 fs/dlm/lowcomms.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 9f14ea9f6..ea18b9478 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -1081,9 +1081,12 @@ static int accept_from_sock(void)
 		add_sock(newsock, newcon);
 
 		/* check if we receved something while adding */
-		lock_sock(newcon->sock->sk);
-		lowcomms_queue_rwork(newcon);
-		release_sock(newcon->sock->sk);
+		if (newcon->sock) {
+			lock_sock(newcon->sock->sk);
+			lowcomms_queue_rwork(newcon);
+			release_sock(newcon->sock->sk);
+		}
+
 	}
 	up_write(&newcon->sock_lock);
 	srcu_read_unlock(&connections_srcu, idx);
-- 
2.25.1