netdev - Re: [PATCH] sr9700: sanity check for packet length

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Date:   Thu, 17 Feb 2022 12:03:10 -0800
From:   Grant Grundler <grundler@...omium.org>
To:     Oliver Neukum <oneukum@...e.com>
Cc:     David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Grant Grundler <grundler@...omium.org>,
        Andrew Lunn <andrew@...n.ch>, jgg@...pe.ca,
        linux-usb@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
        netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH] sr9700: sanity check for packet length

On Thu, Feb 17, 2022 at 5:10 AM Oliver Neukum <oneukum@...e.com> wrote:
>
> A malicious device can leak heap data to user space
> providing bogus frame lengths. Introduce a sanity check.
>
> Signed-off-by: Oliver Neukum <oneukum@...e.com>

Reviewed-by: Grant Grundler <grundler@...omium.org>

> ---
>  drivers/net/usb/sr9700.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/usb/sr9700.c b/drivers/net/usb/sr9700.c
> index b658510cc9a4..5a53e63d33a6 100644
> --- a/drivers/net/usb/sr9700.c
> +++ b/drivers/net/usb/sr9700.c
> @@ -413,7 +413,7 @@ static int sr9700_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
>                 /* ignore the CRC length */
>                 len = (skb->data[1] | (skb->data[2] << 8)) - 4;
>
> -               if (len > ETH_FRAME_LEN)
> +               if (len > ETH_FRAME_LEN || len > skb->len)

good catch.

>                         return 0;
>
>                 /* the last packet of current skb */
> --
> 2.34.1
>