mmc: moxart: Fix reference count leaks in moxart_probe

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. In correspondence with the changes in moxart_probe(),
IS_ERR() is replaced with IS_ERR_OR_NULL() in moxart_remove() as well.

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>
Link: https://lore.kernel.org/r/20211009041918.28419-1-xiongx18@fudan.edu.cn
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/host/moxart-mmc.c b/drivers/mmc/host/moxart-mmc.c
index 6c9d381..7b9fcef 100644 (file)
--- 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;
@@ -687,9 +699,9 @@ static int moxart_remove(struct platform_device *pdev)
 
        dev_set_drvdata(&pdev->dev, NULL);
 
-       if (!IS_ERR(host->dma_chan_tx))
+       if (!IS_ERR_OR_NULL(host->dma_chan_tx))
                dma_release_channel(host->dma_chan_tx);
-       if (!IS_ERR(host->dma_chan_rx))
+       if (!IS_ERR_OR_NULL(host->dma_chan_rx))
                dma_release_channel(host->dma_chan_rx);
        mmc_remove_host(mmc);
        mmc_free_host(mmc);