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From:   Xin Xiong <xiongx18@fudan.edu.cn>
To:     Ulf Hansson <ulf.hansson@linaro.org>, linux-mmc@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     yuanxzhang@fudan.edu.cn, Xin Xiong <xiongx18@fudan.edu.cn>,
        Xiyu Yang <xiyuyang19@fudan.edu.cn>,
        Xin Tan <tanxin.ctf@gmail.com>
Subject: [PATCH v2] drivers/mmc: fix reference count leaks in moxart_probe
Date:   Mon, 27 Sep 2021 09:57:59 +0800
Message-Id: <20210927015759.30855-1-xiongx18@fudan.edu.cn>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The issue happens in several error handling paths on two refcounted
object related to the object "host" (dma_chan_rx, dma_chan_tx). In
these paths, the function forgets to decrement one or both objects'
reference count increased earlier by dma_request_chan(), causing
reference count leaks.

Fix it by balancing the refcounts of both objects in some error
handling paths.

Signed-off-by: Xin Xiong <xiongx18@fudan.edu.cn>
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
---
 drivers/mmc/host/moxart-mmc.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/mmc/host/moxart-mmc.c b/drivers/mmc/host/moxart-mmc.c
index 6c9d38132..e27ab3446 100644
--- a/drivers/mmc/host/moxart-mmc.c
+++ b/drivers/mmc/host/moxart-mmc.c
@@ -621,6 +621,14 @@ static int moxart_probe(struct platform_device *pdev)
 			ret = -EPROBE_DEFER;
 			goto out;
 		}
+        if (!IS_ERR(host->dma_chan_tx)) {
+            dma_release_channel(host->dma_chan_tx);
+            host->dma_chan_tx = NULL;
+        }
+        if (!IS_ERR(host->dma_chan_rx)) {
+            dma_release_channel(host->dma_chan_rx);
+            host->dma_chan_rx = NULL;
+        }
 		dev_dbg(dev, "PIO mode transfer enabled\n");
 		host->have_dma = false;
 	} else {
@@ -675,6 +683,10 @@ static int moxart_probe(struct platform_device *pdev)
 	return 0;
 
 out:
+    if (!IS_ERR_OR_NULL(host->dma_chan_tx))
+        dma_release_channel(host->dma_chan_tx);
+    if (!IS_ERR_OR_NULL(host->dma_chan_rx))
+        dma_release_channel(host->dma_chan_rx);
 	if (mmc)
 		mmc_free_host(mmc);
 	return ret;
-- 
2.25.1