FAILED: patch "[PATCH] tty/serial: digicolor: fix possible null-ptr-deref in" failed to apply to 4.19-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 447ee1516f19f534a228dda237eddb202f23e163 Mon Sep 17 00:00:00 2001
From: Yang Yingliang <yangyingliang@huawei.com>
Date: Thu, 5 May 2022 20:46:21 +0800
Subject: [PATCH] tty/serial: digicolor: fix possible null-ptr-deref in
 digicolor_uart_probe()

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@huawei.com>
Reviewed-by: Baruch Siach <baruch@tkos.co.il>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220505124621.1592697-1-yangyingliang@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/digicolor-usart.c b/drivers/tty/serial/digicolor-usart.c
index 6d70fea76bb3..e37a917b9dbb 100644
--- a/drivers/tty/serial/digicolor-usart.c
+++ b/drivers/tty/serial/digicolor-usart.c
@@ -471,11 +471,10 @@ static int digicolor_uart_probe(struct platform_device *pdev)
 	if (IS_ERR(uart_clk))
 		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);
+	dp->port.membase = devm_platform_get_and_ioremap_resource(pdev, 0, &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)