[PATCH] spi: ti-qspi: fix use-after-free after DMA setup failure

[Johan Hovold <johan@kernel.org>]

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

Make sure to clear the DMA channel pointer also if buffer allocation
fails to avoid passing a pointer to the released channel to the DMA
engine (or trying to free the channel a second time on late probe errors
or driver unbind).

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

Fixes: c687c46e9e45 ("spi: spi-ti-qspi: Use bounce buffer if read buffer is not DMA'ble")
Link: https://sashiko.dev/#/patchset/20260505072909.618363-1-johan%40kernel.org?part=17
Cc: stable@vger.kernel.org	# 4.12
Cc: Vignesh R <vigneshr@ti.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/spi/spi-ti-qspi.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/spi/spi-ti-qspi.c b/drivers/spi/spi-ti-qspi.c
index 1fbd710d616f..e3b413b9828c 100644
--- a/drivers/spi/spi-ti-qspi.c
+++ b/drivers/spi/spi-ti-qspi.c
@@ -867,6 +867,7 @@ static int ti_qspi_probe(struct platform_device *pdev)
 		dev_err(qspi->dev,
 			"dma_alloc_coherent failed, using PIO mode\n");
 		dma_release_channel(qspi->rx_chan);
+		qspi->rx_chan = NULL;
 		goto no_dma;
 	}
 	host->dma_rx = qspi->rx_chan;
-- 
2.53.0