Re: [PATCH net] netdev-genl: avoid empty messages in queue dump

[Joe Damato <jdamato@fastly.com>]

On Tue, Dec 17, 2024 at 06:25:08PM -0800, Jakub Kicinski wrote:
> Empty netlink responses from do() are not correct (as opposed to
> dump() where not dumping anything is perfectly fine).
> We should return an error if the target object does not exist,
> in this case if the netdev is down it has no queues.
> 
> Fixes: 6b6171db7fc8 ("netdev-genl: Add netlink framework functions for queue")
> Reported-by: syzbot+0a884bc2d304ce4af70f@syzkaller.appspotmail.com
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> ---
> CC: jdamato@fastly.com
> CC: almasrymina@google.com
> CC: sridhar.samudrala@intel.com
> CC: amritha.nambiar@intel.com
> ---
>  net/core/netdev-genl.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
> index 9527dd46e4dc..b4becd4065d9 100644
> --- a/net/core/netdev-genl.c
> +++ b/net/core/netdev-genl.c
> @@ -430,10 +430,10 @@ static int
>  netdev_nl_queue_fill(struct sk_buff *rsp, struct net_device *netdev, u32 q_idx,
>  		     u32 q_type, const struct genl_info *info)
>  {
> -	int err = 0;
> +	int err;
>  
>  	if (!(netdev->flags & IFF_UP))
> -		return err;
> +		return -ENOENT;
>  
>  	err = netdev_nl_queue_validate(netdev, q_idx, q_type);
>  	if (err)

Reviewed-by: Joe Damato <jdamato@fastly.com>