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

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Date:   Tue, 22 Jan 2019 13:57:19 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        Matthias Brugger <matthias.bgg@...il.com>
Cc:     linux-serial@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH] tty: serial: 8250_mtk: Fix potential NULL pointer dereference

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 <gustavo@...eddedor.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