chtls: Added a check to avoid NULL pointer dereference

In case of server removal lookup_stid() may return NULL pointer, which
is used as listen_ctx. So added a check before accessing this pointer.

Fixes: cc35c88a ("crypto : chtls - CPL handler definition")
Signed-off-by: Vinay Kumar Yadav <vinay.yadav@chelsio.com>
Signed-off-by: Ayush Sawal <ayush.sawal@chelsio.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c

@@ -1597,6 +1597,11 @@ static int chtls_pass_establish(struct chtls_dev *cdev, struct sk_buff *skb)
 			sk_wake_async(sk, 0, POLL_OUT);
 
 		data = lookup_stid(cdev->tids, stid);
+		if (!data) {
+			/* listening server close */
+			kfree_skb(skb);
+			goto unlock;
+		}
 		lsk = ((struct listen_ctx *)data)->lsk;
 
 		bh_lock_sock(lsk);