From: Paul Cercueil paul@crapouillou.net
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
--- drivers/dma/dma-jz4780.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
--- a/drivers/dma/dma-jz4780.c +++ b/drivers/dma/dma-jz4780.c @@ -567,11 +567,11 @@ static enum dma_status jz4780_dma_tx_sta 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) { @@ -588,6 +588,7 @@ static enum dma_status jz4780_dma_tx_sta && 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; }