linux-kernel - [PATCH 4.9/4.14/4.19/5.4] tty/serial: digicolor: fix possible null-ptr-deref in digicolor_uart

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Date:   Mon, 16 May 2022 22:10:53 +0800
From:   Yang Yingliang <yangyingliang@...wei.com>
To:     <linux-kernel@...r.kernel.org>, <stable@...r.kernel.org>
CC:     <baruch@...s.co.il>, <gregkh@...uxfoundation.org>
Subject: [PATCH 4.9/4.14/4.19/5.4] tty/serial: digicolor: fix possible null-ptr-deref in digicolor_uart_probe()

commit 7c25a0b89a487878b0691e6524fb5a8827322194 upstream.

It will cause null-ptr-deref when using 'res', if platform_get_resource()
returns NULL, so move using 'res' after devm_ioremap_resource() that
will check it to avoid null-ptr-deref.
And use devm_platform_get_and_ioremap_resource() to simplify code.

Fixes: 5930cb3511df ("serial: driver for Conexant Digicolor USART")
Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
Reviewed-by: Baruch Siach <baruch@...s.co.il>
Cc: stable <stable@...r.kernel.org>
Link: https://lore.kernel.org/r/20220505124621.1592697-1-yangyingliang@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
v1:
  These stable versions don't have devm_platform_get_and_ioremap_resource(),
  so just move using 'res' after devm_ioremap_resource().
---
 drivers/tty/serial/digicolor-usart.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/digicolor-usart.c b/drivers/tty/serial/digicolor-usart.c
index 50ec5f1ac77f4..794864fac6250 100644
--- a/drivers/tty/serial/digicolor-usart.c
+++ b/drivers/tty/serial/digicolor-usart.c
@@ -476,10 +476,10 @@ static int digicolor_uart_probe(struct platform_device *pdev)
 		return PTR_ERR(uart_clk);
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	dp->port.mapbase = res->start;
 	dp->port.membase = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(dp->port.membase))
 		return PTR_ERR(dp->port.membase);
+	dp->port.mapbase = res->start;
 
 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0)
-- 
2.25.1