spi: ep93xx: fix error pointer deref after DMA setup failure

The driver falls back to PIO mode if DMA setup fails during probe.

Make sure to the clear the DMA channel pointers on setup failure to avoid dereferencing an error pointer on later probe errors or driver unbind.

This issue was flagged by Sashiko when reviewing a devres allocation conversion patch.

---
 drivers/spi/spi-ep93xx.c | 2 ++
 1 file changed, 2 insertions(+)

index db50018050e5..f716c9607be4 100644
@@ -582,12 +582,14 @@ static int ep93xx_spi_setup_dma(struct device *dev, struct ep93xx_spi *espi)
 	espi->dma_rx = dma_request_chan(dev, "rx");
 	if (IS_ERR(espi->dma_rx)) {
 		ret = dev_err_probe(dev, PTR_ERR(espi->dma_rx), "rx DMA setup failed");
+		espi->dma_rx = NULL;
 		goto fail_free_page;
 	}
 
 	espi->dma_tx = dma_request_chan(dev, "tx");
 	if (IS_ERR(espi->dma_tx)) {
 		ret = dev_err_probe(dev, PTR_ERR(espi->dma_tx), "tx DMA setup failed");
+		espi->dma_tx = NULL;
 		goto fail_release_rx;
 	}
 

2.53.0

Applied to

https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-7.1

Thanks!

[1/1] spi: ep93xx: fix error pointer deref after DMA setup failure

      https://git.kernel.org/broonie/spi/c/5e121a81667a

All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted.

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Thanks,
Mark