[PATCH 3.2 108/221] spi: dw-mid: avoid potential NULL dereference

[Ben Hutchings]

3.2.69-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

commit c9dafb27c84412fe4b17c3b94cc4ffeef5df1833 upstream.

When DMA descriptor allocation fails we should not try to assign any fields in
the bad descriptor. The patch adds the necessary checks for that.

Fixes: 7063c0d942a1 (spi/dw_spi: add DMA support)
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/spi/spi-dw-mid.c | 6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/spi/spi-dw-mid.c
+++ b/drivers/spi/spi-dw-mid.c
@@ -155,6 +155,9 @@ static int mid_spi_dma_transfer(struct d
 				1,
 				DMA_TO_DEVICE,
 				DMA_PREP_INTERRUPT | DMA_COMPL_SKIP_DEST_UNMAP);
+	if (!txdesc)
+		return NULL;
+
 	txdesc->callback = dw_spi_dma_done;
 	txdesc->callback_param = dws;
 
@@ -177,6 +180,9 @@ static int mid_spi_dma_transfer(struct d
 				1,
 				DMA_FROM_DEVICE,
 				DMA_PREP_INTERRUPT | DMA_COMPL_SKIP_DEST_UNMAP);
+	if (!rxdesc)
+		return NULL;
+
 	rxdesc->callback = dw_spi_dma_done;
 	rxdesc->callback_param = dws;
 

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