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dmaengine: dma-jz4780: Fix race in jz4780_dma_tx_status

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commit baf6fd97b16ea8f981b8a8b04039596f32fc2972 upstream.

The jz4780_dma_tx_status() function would check if a channel's cookie
state was set to 'completed', and if not, it would enter the critical
section. However, in that time frame, the jz4780_dma_chan_irq() function
was able to set the cookie to 'completed', and clear the jzchan->vchan
pointer, which was deferenced in the critical section of the first
function.

Fix this race by checking the channel's cookie state after entering the
critical function and not before.

Fixes: d894fc6046 ("dmaengine: jz4780: add driver for the Ingenic JZ4780 DMA controller")
Cc: stable@vger.kernel.org # v4.0
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Reported-by: Artur Rojek <contact@artur-rojek.eu>
Tested-by: Artur Rojek <contact@artur-rojek.eu>
Link: https://lore.kernel.org/r/20201004140307.885556-1-paul@crapouillou.net
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Paul Cercueil 2020-10-04 16:03:07 +02:00 committed by Greg Kroah-Hartman
parent f707ccb2f1
commit a4f02a81c7
1 changed files with 4 additions and 3 deletions
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7
drivers/dma/dma-jz4780.c
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@ -639,11 +639,11 @@ static enum dma_status jz4780_dma_tx_status(struct dma_chan *chan,
unsigned long flags;
unsigned long residue = 0;
spin_lock_irqsave(&jzchan->vchan.lock, flags);
status = dma_cookie_status(chan, cookie, txstate);
if ((status == DMA_COMPLETE) || (txstate == NULL))
return status;
spin_lock_irqsave(&jzchan->vchan.lock, flags);
goto out_unlock_irqrestore;
vdesc = vchan_find_desc(&jzchan->vchan, cookie);
if (vdesc) {
@ -660,6 +660,7 @@ static enum dma_status jz4780_dma_tx_status(struct dma_chan *chan,
&& jzchan->desc->status & (JZ_DMA_DCS_AR | JZ_DMA_DCS_HLT))
status = DMA_ERROR;
out_unlock_irqrestore:
spin_unlock_irqrestore(&jzchan->vchan.lock, flags);
return status;
}