linux-kernel - [PATCH v2] moxart: fix potential use-after-free on remove path

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Message-Id: <20220127071638.4057899-1-gregkh@linuxfoundation.org>
Date:   Thu, 27 Jan 2022 08:16:38 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Xiyu Yang <xiyuyang19@...an.edu.cn>,
        Xin Xiong <xiongx18@...an.edu.cn>,
        Xin Tan <tanxin.ctf@...il.com>,
        Tony Lindgren <tony@...mide.com>,
        Yang Li <yang.lee@...ux.alibaba.com>,
        linux-mmc@...r.kernel.org, stable <stable@...r.kernel.org>,
        whitehat002 <hackyzh002@...il.com>
Subject: [PATCH v2] moxart: fix potential use-after-free on remove path

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@...aro.org>
Cc: Xiyu Yang <xiyuyang19@...an.edu.cn>
Cc: Xin Xiong <xiongx18@...an.edu.cn>
Cc: Xin Tan <tanxin.ctf@...il.com>
Cc: Tony Lindgren <tony@...mide.com>
Cc: Yang Li <yang.lee@...ux.alibaba.com>
Cc: linux-mmc@...r.kernel.org
Cc: stable <stable@...r.kernel.org>
Reported-by: whitehat002 <hackyzh002@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
v2: changed to only move mmc_free_host() call as per Ulf's request

 drivers/mmc/host/moxart-mmc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mmc/host/moxart-mmc.c b/drivers/mmc/host/moxart-mmc.c
index 16d1c7a43d33..b6eb75f4bbfc 100644
--- a/drivers/mmc/host/moxart-mmc.c
+++ b/drivers/mmc/host/moxart-mmc.c
@@ -705,12 +705,12 @@ static int moxart_remove(struct platform_device *pdev)
 	if (!IS_ERR_OR_NULL(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;
 }
-- 
2.35.0