Commit baf6fd97 authored Oct 04, 2020 by Paul Cercueil Committed by Vinod Koul Oct 05, 2020

dmaengine: dma-jz4780: Fix race in jz4780_dma_tx_status



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: d894fc60 ("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>

parent a841592f

drivers/dma/dma-jz4780.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -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;
		}

Admin message