[PATCH] spi: fix NULL pointer dereferences by checking dmaengine_prep_slave_sg

[Kangjie Lu <kjlu@xxxxxxx>]

In case dmaengine_prep_slave_sg fails, the fix returns to avoid
NULL pointer dereference.

Signed-off-by: Kangjie Lu <kjlu@xxxxxxx>
---
 drivers/spi/spi-s3c64xx.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 7b7151ec14c8..3a5f161ce558 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -293,6 +293,8 @@ static void prepare_dma(struct s3c64xx_spi_dma_data *dma,
 
 	desc = dmaengine_prep_slave_sg(dma->ch, sgt->sgl, sgt->nents,
 				       dma->direction, DMA_PREP_INTERRUPT);
+	if (!desc)
+		return;
 
 	desc->callback = s3c64xx_spi_dmacb;
 	desc->callback_param = dma;
-- 
2.17.1