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authorSebastian von Ohr <vonohr@smaract.com>2020-03-03 14:05:18 +0100
committerVinod Koul <vkoul@kernel.org>2020-04-15 21:42:11 +0530
commitb269426011bcfd97b7c3101abfe1a99147b6f40b (patch)
tree96e729dae0ec64fd5aa4dfff5de6f9975ed9c7ad /drivers/dma
parent172d59ecd61b89f535ad99a7e531c0f111453b9a (diff)
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>
Diffstat (limited to 'drivers/dma')
-rw-r--r--drivers/dma/xilinx/xilinx_dma.c20
1 files changed, 10 insertions, 10 deletions
diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
index aecd5a35a296..5429497d3560 100644
--- a/drivers/dma/xilinx/xilinx_dma.c
+++ b/drivers/dma/xilinx/xilinx_dma.c
@@ -1230,16 +1230,16 @@ static enum dma_status xilinx_dma_tx_status(struct dma_chan *dchan,
return ret;
spin_lock_irqsave(&chan->lock, flags);
-
- desc = list_last_entry(&chan->active_list,
- struct xilinx_dma_tx_descriptor, node);
- /*
- * VDMA and simple mode do not support residue reporting, so the
- * residue field will always be 0.
- */
- if (chan->has_sg && chan->xdev->dma_config->dmatype != XDMA_TYPE_VDMA)
- residue = xilinx_dma_get_residue(chan, desc);
-
+ if (!list_empty(&chan->active_list)) {
+ desc = list_last_entry(&chan->active_list,
+ struct xilinx_dma_tx_descriptor, node);
+ /*
+ * VDMA and simple mode do not support residue reporting, so the
+ * residue field will always be 0.
+ */
+ 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);