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

[Kangjie Lu]

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

Signed-off-by: Kangjie Lu <k...@umn.edu>
---
 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