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

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Date:   Mon, 31 Jan 2022 15:39:06 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.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: Re: [PATCH v2] moxart: fix potential use-after-free on remove path

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

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
>