linux-kernel - Re: [PATCH v1] net: macb: fix use after free on rmmod

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Date:   Wed, 8 Sep 2021 07:27:03 +0000
From:   <Nicolas.Ferre@...rochip.com>
To:     <ztong0001@...il.com>, <Claudiu.Beznea@...rochip.com>,
        <davem@...emloft.net>, <kuba@...nel.org>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] net: macb: fix use after free on rmmod

On 07/09/2021 at 22:29, Tong Zhang wrote:
> plat_dev->dev->platform_data is released by platform_device_unregister(),
> use of pclk and hclk is use after free. This patch keeps a copy to fix
> the issue.
> 
> [   31.261225] BUG: KASAN: use-after-free in macb_remove+0x77/0xc6 [macb_pci]
> [   31.275563] Freed by task 306:
> [   30.276782]  platform_device_release+0x25/0x80
> 
> Signed-off-by: Tong Zhang <ztong0001@...il.com>
> ---
>   drivers/net/ethernet/cadence/macb_pci.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/cadence/macb_pci.c b/drivers/net/ethernet/cadence/macb_pci.c
> index 8b7b59908a1a..4dd0cec2e542 100644
> --- a/drivers/net/ethernet/cadence/macb_pci.c
> +++ b/drivers/net/ethernet/cadence/macb_pci.c
> @@ -110,10 +110,12 @@ static void macb_remove(struct pci_dev *pdev)
>   {
>          struct platform_device *plat_dev = pci_get_drvdata(pdev);
>          struct macb_platform_data *plat_data = dev_get_platdata(&plat_dev->dev);
> +       struct clk *pclk = plat_data->pclk;
> +       struct clk *hclk = plat_data->hclk;
> 
>          platform_device_unregister(plat_dev);
> -       clk_unregister(plat_data->pclk);
> -       clk_unregister(plat_data->hclk);
> +       clk_unregister(pclk);
> +       clk_unregister(hclk);

NACK, I  would prefer that you switch lines and do clock clk unregister 
before: this way we avoid the problem and I think that you don't need 
clocks for unregistering the platform device anyway.

Please change accordingly or tell me what could go bad.

Regards,
   Nicolas


>   }
> 
>   static const struct pci_device_id dev_id_table[] = {
> --
> 2.25.1
> 


-- 
Nicolas Ferre