Subject: Re: [PATCH v2] net: usb: rtl8150: don't incorrectly assign random MAC addresses

From: Stephen Rothwell <[email-masked]>
Date: Fri, 16 Oct 2020 08:59:22 +1100

Hi Greg,

On Mon, 12 Oct 2020 09:14:28 +1100 Stephen Rothwell <[email-masked]> wrote:
>
> On Sun, 11 Oct 2020 23:00:30 +0530 Anant Thazhemadam <[email-masked]> wrote:
> >
> > In set_ethernet_addr(), if get_registers() succeeds, the ethernet address
> > that was read must be copied over. Otherwise, a random ethernet address
> > must be assigned.
> > 
> > get_registers() returns 0 if successful, and negative error number
> > otherwise. However, in set_ethernet_addr(), this return value is
> > incorrectly checked.
> > 
> > Since this return value will never be equal to sizeof(node_id), a
> > random MAC address will always be generated and assigned to the
> > device; even in cases when get_registers() is successful.
> > 
> > Correctly modifying the condition that checks if get_registers() was
> > successful or not fixes this problem, and copies the ethernet address
> > appropriately.
> > 
> > Fixes: f45a4248ea4c ("net: usb: rtl8150: set random MAC address when set_ethernet_addr() fails")
> > Signed-off-by: Anant Thazhemadam <[email-masked]>
> > ---
> > Changes in v2:
> >         * Fixed the format of the Fixes tag
> >         * Modified the commit message to better describe the issue being 
> >           fixed
> > 
> > +CCing Stephen and linux-next, since the commit fixed isn't in the networking
> > tree, but is present in linux-next.
> > 
> >  drivers/net/usb/rtl8150.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/usb/rtl8150.c b/drivers/net/usb/rtl8150.c
> > index f020401adf04..bf8a60533f3e 100644
> > --- a/drivers/net/usb/rtl8150.c
> > +++ b/drivers/net/usb/rtl8150.c
> > @@ -261,7 +261,7 @@ static void set_ethernet_addr(rtl8150_t *dev)
> >  
> >  	ret = get_registers(dev, IDR, sizeof(node_id), node_id);
> >  
> > -	if (ret == sizeof(node_id)) {
> > +	if (!ret) {
> >  		ether_addr_copy(dev->netdev->dev_addr, node_id);
> >  	} else {
> >  		eth_hw_addr_random(dev->netdev);
> > -- 
> > 2.25.1
> >   
> 
> I will apply the above patch to the merge of the usb tree today to fix
> up a semantic conflict between the usb tree and Linus' tree.

It looks like you forgot to mention this one to Linus :-(

It should probably say:

Fixes: b2a0f274e3f7 ("net: rtl8150: Use the new usb control message API.")

-- 
Cheers,
Stephen Rothwell