linux-kernel - [Patch] serial: 8250_bcm7271: fix leak in `brcmuart

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Date:   Mon, 24 Apr 2023 20:51:00 +0800
From:   XuDong Liu <m202071377@...t.edu.cn>
To:     Al Cooper <alcooperx@...il.com>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Doug Berger <opendmb@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>
Cc:     XuDong Liu <m202071377@...t.edu.cn>,
        Dongliang Mu <dzm91@...t.edu.cn>, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [Patch] serial: 8250_bcm7271: fix leak in `brcmuart_probe`

Smatch reports:
drivers/tty/serial/8250/8250_bcm7271.c:1120 brcmuart_probe() warn: 
'baud_mux_clk' from clk_prepare_enable() not released on lines: 1032.

In the function brcmuart_probe(), baud_mux_clk was not correctly released
in subsequent error handling, which may cause memory leaks.

To fix this issue, an error handling branch, err_clk_put, is added to
release the variable using clk_put(), and an err_disable branch is added
to meet the requirement of balancing clk_disable and clk_enable calls.

Fixes: 15ac1122fd6d ("serial: 8250_bcm7271: Fix arbitration handling")
Signed-off-by: XuDong Liu <m202071377@...t.edu.cn>
Reviewed-by: Dongliang Mu <dzm91@...t.edu.cn>
---
The issue is discovered by static analysis, and the patch is not tested
yet.
---
 drivers/tty/serial/8250/8250_bcm7271.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_bcm7271.c b/drivers/tty/serial/8250/8250_bcm7271.c
index f801b1f5b46c..b1670558868b 100644
--- a/drivers/tty/serial/8250/8250_bcm7271.c
+++ b/drivers/tty/serial/8250/8250_bcm7271.c
@@ -1023,7 +1023,7 @@ static int brcmuart_probe(struct platform_device *pdev)
 		dev_dbg(dev, "BAUD MUX clock found\n");
 		ret = clk_prepare_enable(baud_mux_clk);
 		if (ret)
-			goto release_dma;
+			goto err_clk_put;
 		priv->baud_mux_clk = baud_mux_clk;
 		init_real_clk_rates(dev, priv);
 		clk_rate = priv->default_mux_rate;
@@ -1032,7 +1032,7 @@ static int brcmuart_probe(struct platform_device *pdev)
 	if (clk_rate == 0) {
 		dev_err(dev, "clock-frequency or clk not defined\n");
 		ret = -EINVAL;
-		goto release_dma;
+		goto err_clk_disable;
 	}
 
 	dev_dbg(dev, "DMA is %senabled\n", priv->dma_enabled ? "" : "not ");
@@ -1119,6 +1119,10 @@ static int brcmuart_probe(struct platform_device *pdev)
 	serial8250_unregister_port(priv->line);
 err:
 	brcmuart_free_bufs(dev, priv);
+err_clk_disable:
+	clk_disable_unprepare(baud_mux_clk);
+err_clk_put:
+	clk_put(baud_mux_clk);
 release_dma:
 	if (priv->dma_enabled)
 		brcmuart_arbitration(priv, 0);
-- 
2.34.1