[PATCH] tty: serial: 8250_mtk: Fix potential NULL pointer dereference

[Gustavo A. R. Silva]

There is a potential NULL pointer dereference in case devm_kzalloc()
fails and returns NULL.

Fix this by adding a NULL check on data->dma

This bug was detected with the help of Coccinelle.

Fixes: 85b5c1dd0456 ("serial: 8250-mtk: add uart DMA support")
Signed-off-by: Gustavo A. R. Silva <gust...@embeddedor.com>
---
 drivers/tty/serial/8250/8250_mtk.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_mtk.c 
b/drivers/tty/serial/8250/8250_mtk.c
index e2c407656fa6..c1fdbc0b6840 100644
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -357,6 +357,9 @@ static int mtk8250_probe_of(struct platform_device *pdev, 
struct uart_port *p,
        if (dmacnt == 2) {
                data->dma = devm_kzalloc(&pdev->dev, sizeof(*data->dma),
                                         GFP_KERNEL);
+               if (!data->dma)
+                       return -ENOMEM;
+
                data->dma->fn = mtk8250_dma_filter;
                data->dma->rx_size = MTK_UART_RX_SIZE;
                data->dma->rxconf.src_maxburst = MTK_UART_RX_TRIGGER;
-- 
2.20.1