spi: bcm2835: bcm2835_spi_handle_err(): fix NULL pointer deref for non DMA transfers

In case a IRQ based transfer times out the bcm2835_spi_handle_err()
function is called. Since commit 1513ceee70f2 ("spi: bcm2835: Drop
dma_pending flag") the TX and RX DMA transfers are unconditionally
canceled, leading to NULL pointer derefs if ctlr->dma_tx or
ctlr->dma_rx are not set.

Fix the NULL pointer deref by checking that ctlr->dma_tx and
ctlr->dma_rx are valid pointers before accessing them.

Fixes: 1513ceee70f2 ("spi: bcm2835: Drop dma_pending flag")
Cc: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/20220719072234.2782764-1-mkl@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index 775c0bf..0933948 100644 (file)
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -1138,10 +1138,14 @@ static void bcm2835_spi_handle_err(struct spi_controller *ctlr,
        struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);
 
        /* if an error occurred and we have an active dma, then terminate */
-       dmaengine_terminate_sync(ctlr->dma_tx);
-       bs->tx_dma_active = false;
-       dmaengine_terminate_sync(ctlr->dma_rx);
-       bs->rx_dma_active = false;
+       if (ctlr->dma_tx) {
+               dmaengine_terminate_sync(ctlr->dma_tx);
+               bs->tx_dma_active = false;
+       }
+       if (ctlr->dma_rx) {
+               dmaengine_terminate_sync(ctlr->dma_rx);
+               bs->rx_dma_active = false;
+       }
        bcm2835_spi_undo_prologue(bs);
 
        /* and reset */