linux-kernel - [PATCH v2] serial: pch_uart: potential dereference of null pointer

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Message-Id: <20211216125121.399938-1-jiasheng@iscas.ac.cn>
Date:   Thu, 16 Dec 2021 20:51:21 +0800
From:   Jiasheng Jiang <jiasheng@...as.ac.cn>
To:     gregkh@...uxfoundation.org, jirislaby@...nel.org
Cc:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jiasheng Jiang <jiasheng@...as.ac.cn>
Subject: [PATCH v2] serial: pch_uart: potential dereference of null pointer

The return value of dma_alloc_coherent() needs to be checked.
To avoid dereference of null pointer in case of the failure of alloc.

Fixes: ab4382d27412 ("tty: move drivers/serial/ to drivers/tty/serial/")
Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
---
Changelog:

v1 -> v2

*Change 1. Add the dev_err when dma_alloc_coherent failed.
---
 drivers/tty/serial/pch_uart.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
index f0351e6f0ef6..d19ed7da24fa 100644
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -745,6 +745,14 @@ static void pch_request_dma(struct uart_port *port)
 	/* Get Consistent memory for DMA */
 	priv->rx_buf_virt = dma_alloc_coherent(port->dev, port->fifosize,
 				    &priv->rx_buf_dma, GFP_KERNEL);
+	if (!priv->rx_buf_virt) {
+		dev_err(priv->port.dev, "%s:dma_alloc_coherent FAILS(Rx)\n",
+			__func__);
+		dma_release_channel(priv->chan_tx);
+		priv->chan_tx = NULL;
+		return;
+	}
+
 	priv->chan_rx = chan;
 }
 
-- 
2.25.1