From a4f02a81c7e6ce74be47ff7ba45b60c39e82eb5b Mon Sep 17 00:00:00 2001 From: Paul Cercueil Date: Sun, 4 Oct 2020 16:03:07 +0200 Subject: [PATCH] dmaengine: dma-jz4780: Fix race in jz4780_dma_tx_status 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 Reported-by: Artur Rojek Tested-by: Artur Rojek Link: https://lore.kernel.org/r/20201004140307.885556-1-paul@crapouillou.net Signed-off-by: Vinod Koul Signed-off-by: Greg Kroah-Hartman --- 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 0ecb724b394f5..e27043427653f 100644 --- a/drivers/dma/dma-jz4780.c +++ b/drivers/dma/dma-jz4780.c @@ -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; }