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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.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, whitehat002 <hackyzh002@gmail.com>
Subject: [PATCH 4.19 2/2] moxart: fix potential use-after-free on remove path
Date:   Wed,  9 Feb 2022 20:14:04 +0100
Message-Id: <20220209191248.685713468@linuxfoundation.org>
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References: <20220209191248.596319706@linuxfoundation.org>
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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit bd2db32e7c3e35bd4d9b8bbff689434a50893546 upstream.

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>
Link: https://lore.kernel.org/r/20220127071638.4057899-1-gregkh@linuxfoundation.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/mmc/host/moxart-mmc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/mmc/host/moxart-mmc.c
+++ b/drivers/mmc/host/moxart-mmc.c
@@ -696,12 +696,12 @@ static int moxart_remove(struct platform
 		if (!IS_ERR(host->dma_chan_rx))
 			dma_release_channel(host->dma_chan_rx);
 		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);
+		mmc_free_host(mmc);
 	}
 	return 0;
 }