spi: stm32: fix potential dereference null return value

This patch fixes the usage of rx_dma_desc and tx_dma_desc pointers
returned by dmaengine_prep_slave_sg, which can be null.

Detected by CoverityScan, CID#1446587 ("Dereference null return value")

Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
index 8a6bff3..75644bc 100644 (file)
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -775,9 +775,6 @@ static int stm32_spi_transfer_one_dma(struct stm32_spi *spi,
                                        xfer->rx_sg.nents,
                                        rx_dma_conf.direction,
                                        DMA_PREP_INTERRUPT);
-
-               rx_dma_desc->callback = stm32_spi_dma_cb;
-               rx_dma_desc->callback_param = spi;
        }
 
        tx_dma_desc = NULL;
@@ -790,11 +787,6 @@ static int stm32_spi_transfer_one_dma(struct stm32_spi *spi,
                                        xfer->tx_sg.nents,
                                        tx_dma_conf.direction,
                                        DMA_PREP_INTERRUPT);
-
-               if (spi->cur_comm == SPI_SIMPLEX_TX) {
-                       tx_dma_desc->callback = stm32_spi_dma_cb;
-                       tx_dma_desc->callback_param = spi;
-               }
        }
 
        if ((spi->tx_buf && !tx_dma_desc) ||
@@ -802,6 +794,9 @@ static int stm32_spi_transfer_one_dma(struct stm32_spi *spi,
                goto dma_desc_error;
 
        if (rx_dma_desc) {
+               rx_dma_desc->callback = stm32_spi_dma_cb;
+               rx_dma_desc->callback_param = spi;
+
                if (dma_submit_error(dmaengine_submit(rx_dma_desc))) {
                        dev_err(spi->dev, "Rx DMA submit failed\n");
                        goto dma_desc_error;
@@ -811,6 +806,11 @@ static int stm32_spi_transfer_one_dma(struct stm32_spi *spi,
        }
 
        if (tx_dma_desc) {
+               if (spi->cur_comm == SPI_SIMPLEX_TX) {
+                       tx_dma_desc->callback = stm32_spi_dma_cb;
+                       tx_dma_desc->callback_param = spi;
+               }
+
                if (dma_submit_error(dmaengine_submit(tx_dma_desc))) {
                        dev_err(spi->dev, "Tx DMA submit failed\n");
                        goto dma_submit_error;