Commit b2694260 authored Mar 03, 2020 by Sebastian von Ohr Committed by Vinod Koul Apr 15, 2020

dmaengine: xilinx_dma: Add missing check for empty list



The DMA transfer might finish just after checking the state with
dma_cookie_status, but before the lock is acquired. Not checking
for an empty list in xilinx_dma_tx_status may result in reading
random data or data corruption when desc is written to. This can
be reliably triggered by using dma_sync_wait to wait for DMA
completion.

Signed-off-by: Sebastian von Ohr <vonohr@smaract.com>
Tested-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Link: https://lore.kernel.org/r/20200303130518.333-1-vonohr@smaract.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>

parent 172d59ec

drivers/dma/xilinx/xilinx_dma.c

+10 −10

Original line number	Diff line number	Diff line
		@@ -1230,7 +1230,7 @@ static enum dma_status xilinx_dma_tx_status(struct dma_chan *dchan,
		return ret;

		spin_lock_irqsave(&chan->lock, flags);

		if (!list_empty(&chan->active_list)) {
		desc = list_last_entry(&chan->active_list,
		struct xilinx_dma_tx_descriptor, node);
		/*
		@@ -1239,7 +1239,7 @@ static enum dma_status xilinx_dma_tx_status(struct dma_chan *dchan,
		*/
		if (chan->has_sg && chan->xdev->dma_config->dmatype != XDMA_TYPE_VDMA)
		residue = xilinx_dma_get_residue(chan, desc);

		}
		spin_unlock_irqrestore(&chan->lock, flags);

		dma_set_residue(txstate, residue);

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