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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>
This commit is contained in:
M'boumba Cedric Madianga 2016-12-13 14:40:46 +01:00 committed by Vinod Koul
parent 7e96304d99
commit 57b5a32135
1 changed files with 3 additions and 7 deletions
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10
drivers/dma/stm32-dma.c
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@ -880,7 +880,7 @@ static enum dma_status stm32_dma_tx_status(struct dma_chan *c,
struct virt_dma_desc *vdesc; struct virt_dma_desc *vdesc;
enum dma_status status; enum dma_status status;
unsigned long flags; unsigned long flags;
u32 residue; u32 residue = 0;
status = dma_cookie_status(c, cookie, state); status = dma_cookie_status(c, cookie, state);
if ((status == DMA_COMPLETE) || (!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); spin_lock_irqsave(&chan->vchan.lock, flags);
vdesc = vchan_find_desc(&chan->vchan, cookie); 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, residue = stm32_dma_desc_residue(chan, chan->desc,
chan->next_sg); chan->next_sg);
} else if (vdesc) { else if (vdesc)
residue = stm32_dma_desc_residue(chan, residue = stm32_dma_desc_residue(chan,
to_stm32_dma_desc(vdesc), 0); to_stm32_dma_desc(vdesc), 0);
} else {
residue = 0;
}
dma_set_residue(state, residue); dma_set_residue(state, residue);
spin_unlock_irqrestore(&chan->vchan.lock, flags); spin_unlock_irqrestore(&chan->vchan.lock, flags);