From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Xiyu Yang <xiyuyang19@fudan.edu.cn>,
        Xin Xiong <xiongx18@fudan.edu.cn>,
        Xin Tan <tanxin.ctf@gmail.com>,
        Tony Lindgren <tony@atomide.com>,
        Yang Li <yang.lee@linux.alibaba.com>,
        linux-mmc@vger.kernel.org, stable <stable@vger.kernel.org>,
        whitehat002 <hackyzh002@gmail.com>
Subject: [PATCH] moxart: fix potential use-after-free on remove path
Date:   Fri, 14 Jan 2022 08:59:34 +0100
Message-Id: <20220114075934.302464-1-gregkh@linuxfoundation.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

It was reported that the mmc host structure could be accessed after it
was freed in moxart_remove(), so fix this by saving the base register of
the device and using it instead of the pointer dereference.

Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Cc: Xin Xiong <xiongx18@fudan.edu.cn>
Cc: Xin Tan <tanxin.ctf@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Yang Li <yang.lee@linux.alibaba.com>
Cc: linux-mmc@vger.kernel.org
Cc: stable <stable@vger.kernel.org>
Reported-by: whitehat002 <hackyzh002@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/mmc/host/moxart-mmc.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/host/moxart-mmc.c b/drivers/mmc/host/moxart-mmc.c
index 16d1c7a43d33..f5d96940a9b8 100644
--- a/drivers/mmc/host/moxart-mmc.c
+++ b/drivers/mmc/host/moxart-mmc.c
@@ -697,6 +697,7 @@ static int moxart_remove(struct platform_device *pdev)
 {
 	struct mmc_host *mmc = dev_get_drvdata(&pdev->dev);
 	struct moxart_host *host = mmc_priv(mmc);
+	void __iomem *base = host->base;
 
 	dev_set_drvdata(&pdev->dev, NULL);
 
@@ -707,10 +708,10 @@ static int moxart_remove(struct platform_device *pdev)
 	mmc_remove_host(mmc);
 	mmc_free_host(mmc);
 
-	writel(0, host->base + REG_INTERRUPT_MASK);
-	writel(0, host->base + REG_POWER_CONTROL);
-	writel(readl(host->base + REG_CLOCK_CONTROL) | CLK_OFF,
-	       host->base + REG_CLOCK_CONTROL);
+	writel(0, base + REG_INTERRUPT_MASK);
+	writel(0, base + REG_POWER_CONTROL);
+	writel(readl(base + REG_CLOCK_CONTROL) | CLK_OFF,
+	       base + REG_CLOCK_CONTROL);
 
 	return 0;
 }
-- 
2.34.1