From: Paul Cercueil <paul@crapouillou.net> stable inclusion from linux-4.19.155 commit fd9079bdc25c2d004da5294f91ddaf844818618a -------------------------------- 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: d894fc6046fe ("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> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- drivers/dma/dma-jz4780.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c index edff93aacad3..0d0850b35e45 100644 --- a/drivers/dma/dma-jz4780.c +++ b/drivers/dma/dma-jz4780.c @@ -574,11 +574,11 @@ static enum dma_status jz4780_dma_tx_status(struct dma_chan *chan, enum dma_status status; unsigned long flags; + 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) { @@ -595,6 +595,7 @@ 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; } -- 2.25.1