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

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

[Greg Kroah-Hartman]

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>
---
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

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

[Ulf Hansson]

On Thu, 27 Jan 2022 at 08:16, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> 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>

Applied for fixes, thanks!

Kind regards
Uffe

> ---
> 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
>