netdev - Re: [PATCH net-next v2 1/2] usbnet: ipheth: fix risk of NULL pointer deallocation

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Message-ID: <ZHBlShZDu3C8VOl3@corigine.com>
Date: Fri, 26 May 2023 09:52:42 +0200
From: Simon Horman <simon.horman@...igine.com>
To: Foster Snowhill <forst@....gy>
Cc: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Georgi Valkov <gvalkov@...il.com>, linux-usb@...r.kernel.org,
	netdev@...r.kernel.org
Subject: Re: [PATCH net-next v2 1/2] usbnet: ipheth: fix risk of NULL pointer
 deallocation

On Thu, May 25, 2023 at 09:42:54PM +0200, Foster Snowhill wrote:
> From: Georgi Valkov <gvalkov@...il.com>
> 
> The cleanup precedure in ipheth_probe will attempt to free a
> NULL pointer in dev->ctrl_buf if the memory allocation for
> this buffer is not successful. Rearrange the goto labels to
> avoid this risk.

Hi Georgi and Foster,

kfree will ignore a NULL argument, so I think the existing code is safe.
But given the name of the label I do agree there is scope for a cleanup
here.

Could you consider rewording the patch description accordingly?

> Signed-off-by: Georgi Valkov <gvalkov@...il.com>

If Georgi is the author of the patch, which seems to be the case,
then the above is correct. But as the patch is being posted by Foster
I think it should be followed by a Signed-off-by line for Foster.

Link: https://www.kernel.org/doc/html/latest/process/submitting-patches.html?highlight=signed+off#developer-s-certificate-of-origin-1-1

> ---
>  drivers/net/usb/ipheth.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/usb/ipheth.c b/drivers/net/usb/ipheth.c
> index 6a769df0b..8875a3d0e 100644
> --- a/drivers/net/usb/ipheth.c
> +++ b/drivers/net/usb/ipheth.c
> @@ -510,8 +510,8 @@ static int ipheth_probe(struct usb_interface *intf,
>         ipheth_free_urbs(dev);
>  err_alloc_urbs:
>  err_get_macaddr:
> -err_alloc_ctrl_buf:
>         kfree(dev->ctrl_buf);
> +err_alloc_ctrl_buf:
>  err_endpoints:
>         free_netdev(netdev);
>         return retval;

-- 
pw-bot: cr