dmaengine: stm32-dma: Fix null pointer dereference in stm32_dma_tx_status

chan->desc is always set to NULL when a DMA transfer is complete.
As a DMA transfer could be complete during the call of stm32_dma_tx_status,
we need to be sure that chan->desc is not NULL before using this variable
to avoid a null pointer deference issue.

Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
Reviewed-by: Ludovic BARRE <ludovic.barre@st.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
index a884b857cba44b90f5598ea2f78821b157c25ad1..3056ce7f8c69d01c61fe3ab0eeff6ad299f538f7 100644 (file)
--- a/drivers/dma/stm32-dma.c
+++ b/drivers/dma/stm32-dma.c
@@ -880,7 +880,7 @@ static enum dma_status stm32_dma_tx_status(struct dma_chan *c,
        struct virt_dma_desc *vdesc;
        enum dma_status status;
        unsigned long flags;
-       u32 residue;
+       u32 residue = 0;
 
        status = dma_cookie_status(c, cookie, state);
        if ((status == DMA_COMPLETE) || (!state))
@@ -888,16 +888,12 @@ static enum dma_status stm32_dma_tx_status(struct dma_chan *c,
 
        spin_lock_irqsave(&chan->vchan.lock, flags);
        vdesc = vchan_find_desc(&chan->vchan, cookie);
-       if (cookie == chan->desc->vdesc.tx.cookie) {
+       if (chan->desc && cookie == chan->desc->vdesc.tx.cookie)
                residue = stm32_dma_desc_residue(chan, chan->desc,
                                                 chan->next_sg);
-       } else if (vdesc) {
+       else if (vdesc)
                residue = stm32_dma_desc_residue(chan,
                                                 to_stm32_dma_desc(vdesc), 0);
-       } else {
-               residue = 0;
-       }
-
        dma_set_residue(state, residue);
 
        spin_unlock_irqrestore(&chan->vchan.lock, flags);