Re: [PATCH] usb: rtl8150: avoid using uninitialized CSCR value

[Simon Horman <horms@kernel.org>]

On Thu, Apr 02, 2026 at 03:07:43PM +0800, Morduan Zang wrote:
> Check get_registers() when reading CSCR in set_carrier().
> If the control transfer fails, don't use the stack value.
> 
> Reported-by: syzbot+9db6c624635564ad813c@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=9db6c624635564ad813c
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Morduan Zang <zhangdandan@uniontech.com>
> ---
>  drivers/net/usb/rtl8150.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/usb/rtl8150.c b/drivers/net/usb/rtl8150.c
> index 4cda0643afb6..7e32726d3e6f 100644
> --- a/drivers/net/usb/rtl8150.c
> +++ b/drivers/net/usb/rtl8150.c
> @@ -722,7 +722,11 @@ static void set_carrier(struct net_device *netdev)
>  	rtl8150_t *dev = netdev_priv(netdev);
>  	short tmp;
>  
> -	get_registers(dev, CSCR, 2, &tmp);
> +	if (get_registers(dev, CSCR, 2, &tmp) < 0) {
> +		netif_carrier_off(netdev);
> +		return;
> +	}
> +
>  	if (tmp & CSCR_LINK_STATUS)
>  		netif_carrier_on(netdev);
>  	else

I wonder if we can handle this a bit more succinctly,
while still making it clear that the error is handled.
Something like this:

diff --git a/drivers/net/usb/rtl8150.c b/drivers/net/usb/rtl8150.c
index 4cda0643afb6..816759ced56c 100644
--- a/drivers/net/usb/rtl8150.c
+++ b/drivers/net/usb/rtl8150.c
@@ -722,7 +722,8 @@ static void set_carrier(struct net_device *netdev)
 	rtl8150_t *dev = netdev_priv(netdev);
 	short tmp;
 
-	get_registers(dev, CSCR, 2, &tmp);
+	if (get_registers(dev, CSCR, 2, &tmp) < 0)
+		tmp = 0;
 	if (tmp & CSCR_LINK_STATUS)
 		netif_carrier_on(netdev);
 	else