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    Subject[PATCH 5.15 252/917] mmc: moxart: Fix reference count leaks in moxart_probe
    Date
    From: Xin Xiong <xiongx18@fudan.edu.cn>

    [ Upstream commit 8105c2abbf36296bf38ca44f55ee45d160db476a ]

    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>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/mmc/host/moxart-mmc.c | 16 ++++++++++++++--
    1 file changed, 14 insertions(+), 2 deletions(-)

    diff --git a/drivers/mmc/host/moxart-mmc.c b/drivers/mmc/host/moxart-mmc.c
    index 6c9d38132f74c..7b9fcef490de7 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;
    @@ -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);
    --
    2.33.0


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