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    Subject[PATCH 5.14 800/849] dmaengine: ti: k3-udma: Set bchan to NULL if a channel request fail
    Date
    From: Kishon Vijay Abraham I <kishon@ti.com>

    commit 5c6c6d60e4b489308ae4da8424c869f7cc53cd12 upstream.

    bcdma_get_*() checks if bchan is already allocated by checking if it
    has a NON NULL value. For the error cases, bchan will have error value
    and bcdma_get_*() considers this as already allocated (PASS) since the
    error values are NON NULL. This results in NULL pointer dereference
    error while de-referencing bchan.

    Reset the value of bchan to NULL if a channel request fails.

    CC: stable@vger.kernel.org
    Acked-by: Peter Ujfalusi <peter.ujfalusi@gmail.com>
    Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
    Link: https://lore.kernel.org/r/20211031032411.27235-2-kishon@ti.com
    Signed-off-by: Vinod Koul <vkoul@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/dma/ti/k3-udma.c | 8 ++++++--
    1 file changed, 6 insertions(+), 2 deletions(-)

    --- a/drivers/dma/ti/k3-udma.c
    +++ b/drivers/dma/ti/k3-udma.c
    @@ -1348,6 +1348,7 @@ static int bcdma_get_bchan(struct udma_c
    {
    struct udma_dev *ud = uc->ud;
    enum udma_tp_level tpl;
    + int ret;

    if (uc->bchan) {
    dev_dbg(ud->dev, "chan%d: already have bchan%d allocated\n",
    @@ -1365,8 +1366,11 @@ static int bcdma_get_bchan(struct udma_c
    tpl = ud->bchan_tpl.levels - 1;

    uc->bchan = __udma_reserve_bchan(ud, tpl, -1);
    - if (IS_ERR(uc->bchan))
    - return PTR_ERR(uc->bchan);
    + if (IS_ERR(uc->bchan)) {
    + ret = PTR_ERR(uc->bchan);
    + uc->bchan = NULL;
    + return ret;
    + }

    uc->tchan = uc->bchan;


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