Commit b2694260 authored by Sebastian von Ohr's avatar Sebastian von Ohr Committed by Vinod Koul
Browse files

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


Signed-off-by: default avatarVinod 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);