linux-kernel - [PATCH v2] tty/serial: Check for null pointer after calling devm

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Date:   Fri,  7 Jan 2022 22:48:52 +0800
From:   Jiasheng Jiang <jiasheng@...as.ac.cn>
To:     gregkh@...uxfoundation.org
Cc:     jirislaby@...nel.org, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org, Jiasheng Jiang <jiasheng@...as.ac.cn>
Subject: [PATCH v2] tty/serial: Check for null pointer after calling devm_ioremap

As the possible failure of the devres_alloc(), the devm_ioremap()
may return NULL pointer.
And the 'port->membase' will be used in mlb_usio_startup() without the
check.
Therefore, in order to avoid the dereference of the NULL pointer, it
should be better to add the check to guarantee the success of the probe.

Fixes: ba44dc043004 ("serial: Add Milbeaut serial control")
Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
---
Changelog

v1 -> v2

* Change 1. Refine the commit message to be more clear.
---
 drivers/tty/serial/milbeaut_usio.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/tty/serial/milbeaut_usio.c b/drivers/tty/serial/milbeaut_usio.c
index 8f2cab7f66ad..1ecbf6d0dc79 100644
--- a/drivers/tty/serial/milbeaut_usio.c
+++ b/drivers/tty/serial/milbeaut_usio.c
@@ -523,6 +523,10 @@ static int mlb_usio_probe(struct platform_device *pdev)
 	}
 	port->membase = devm_ioremap(&pdev->dev, res->start,
 				resource_size(res));
+	if (!port->membase) {
+		ret = -ENOMEM;
+		goto failed;
+	}
 
 	ret = platform_get_irq_byname(pdev, "rx");
 	mlb_usio_irq[index][RX] = ret;
-- 
2.25.1